Membranes, mitochondria and amoebae: shape models

Most real-world shapes and images are characterized by high variability- they are not rigid, like crystals, for example—but they are strongly structured. Therefore, a fundamental task in the understanding and analysis of such image ensembles is the construction of models that incorporate both variability and structure in a mathematically precise way. The global shape models introduced in Grenander's general pattern theory are intended to do this. In this paper, we describe the representation of two-dimensional mitochondria and membranes in electron microscope photographs, and three-dimensional amoebae in optical sectioning microscopy. There are three kinds of variability to all of these patterns, which these representations accommodate. The first is the variability in shape and viewing orientation. For this, the typical structure is represented via linear, circular and spherical templates, with the variability accomodated via the application of transformations applied to the templates. The transformations form groups: scale, rotation and translation. They are locally applied throughout the continuum and of high dimension. The second is the textural variability; the inside and outside of these basic shapes are subject to random variation, as well as sensor noise. For this, statistical sensor models and Markov random field texture models are used to connect the constituent structures of the shapes to the measured data. The third variability type is associated with the fact that each scene is made up of a variable number of shapes; this number is not assumed to be known a priori. Each scene has a variable number of parameters encoding the transformations of the templates appropriate for that scene. For this, a single posterior distribution is defined over the countable union of spaces representing models of varying numbers of shapes. Bayesian inference is performed via computation of the conditional expectation of the parametrically defined shapes under the posterior. These conditional mean estimates are generated using jump-diffusion processes. Results for membranes, mitochondria and amoebae are shown.     

INTERGENERATIONAL MOBILITY IN THE REPUBLIC OF IRELAND: Does Gender Make a Difference?

This article compares in regression models the effects of occupational status of both fathers and mothers simultaneously upon the attainment of men and women in the Irish Republic. The sample matches male respondents from the 1973/1974 Irish Mobility Study with the labour active female sibling next closest in age. Since the analysis compares working siblings and each 'matched pair' shares the same family origin characteristics, the problems attendant upon using a sample originally of men only are partially avoided. The results advance beyond previous research since, rather than separate models by gender, models include parents and children of both genders, allowing direct rather than indirect evaluation of gender-based determinants of occupational attainment. Both fathers and mothers significantly affect children's attainment, in ways that vary by the child's gender. The results highlight the salience of mothers' attainment for their children and question the 'mainstream' model of equivalent mechanisms of occupational attainment for both genders. Models of social mobility that consider men and women as special instances of a general perspective provide the most fruitful approach for further development.     

The Influence of the Socio-economic Characteristics of Disabled People on Their Employment Status and Income

Most of the studies of the employment and income levels of disabled people focus on a specific disability or on severely disabled persons. A few studies are cross disability ones, but they fail to go beyond simple associations or else have extremely small sample sizes. There is a need for studies which are cross disability and which have an adequate sample size in order to determine if there are structural variables in society—like a class system-which operate upon the employment opportunities of disabled persons. Using a sample (n = 733) of the Disability Community in Massachusetts, socio-economic variables related to employment and income are studied. Statistically significant relationships are found. Several models are developed and the implications for social theory are discussed.     

Designing ChSP-4(c1, c2) plans

In this paper, the notion of average total inspection (ATI) is introduced to ChSP-4(c1,c2) sampling plans. Procedures have been developed for the construction and selection of ChSP-4(c1, c2 plans, minimizing ATI at a given process average, while protection to the consumer is given in terms of the (i) average outgoing quality limit and (ii) limiting quality level.A wide range of c1 and c2 values are considered for developing tables which cover almost all practical situations. The procedure described is similar to that of Dodge and Romig.     

Traffic Partition in WDM/SONET Rings to Minimize SONET ADMs

SONET (Synchronous Optical NETworks) add-drop multiplexers (ADMs) are the dominant cost factor in the WDM(Wavelength Division Multiplexing)/SONET rings. The number of SONET ADMs required by a set of traffic streams is determined by the routing and wavelength assignment of the traffic streams. Previous works took as input the traffic streams with routings given a priori and developed various heuristics for wavelength assignment to minimize the SONET ADM costs. However, little was known about the performance guarantees of these heuristics. This paper contributes mainly in two aspects. First, in addition to the traffic streams with pre-specified routing, this paper also studies minimizing the ADM requirement by traffic streams without given routings, a problem which is shown to be NP-hard. Several heuristics for integrated routing and wavelength assignment are proposed to minimize the SONET ADM costs. Second, the approximation ratios of those heuristics for wavelength assignment only and those heuristics for integrated routing and wavelength assignment are analyzed. The new Preprocessed Iterative Matching heuristic has the best approximation ratio: at most 3/2.     

Naming Men as Men: Implications for Work,Organization and Management

This paper seeks to contribute to the growing interest in naming men as men as part of a critical analysis of gendered power relations in organizations. The paper highlights the way in which men and masculinities are frequently central to organizational analysis, yet rarely the focus of interrogation. They remain taken for granted and hidden. Examining recent studies that contribute to a critical analysis of gendered power relations, we consider the growing interest in multiplicity, diversity and difference. In particular, we explore the issue of ‘multiple masculinities’ as well as some of the conceptual difficulties that surround it. Arguing for an approach which addresses the unities, differences and interrelations between men and masculinities, we suggest that critical studies of gendered power need to examine the management of organizations in much more detail. Highlighting five masculinities that seem to be routinely embedded in managerial discourses and practices, we conclude by advocating further research in this previously neglected area.     

TEACHING TOOLS: ECONOMICS OF CHILDHOOD IMMUNIZATION

Recent outbreaks of measles and other childhood diseases have put immunization policy on the national agenda. This teaching note on childhood immunization, intended for principles courses, discusses the rationale for government involvement, the situation in the U.S., and the policies of Northern Ireland and Austria. It emphasizes (a) the use of financial incentives to motivate behavior, (b) the distinction between shifting and moving along the demand curve, and (c) the notion of negative prices (i.e., paying the customer to "buy" the item). Students especially like the idea of the demand curve extending below the x-axis.