The numerical range of positive operators on Hilbert lattices

We show symmetry properties of the numerical range of positive operators on Hilbert lattices. These results generalise the respective properties for positive matrices shown in Li etal. (Linear Algebra Appl 350:1-23, 2002) and Maroulas etal. (Linear Algebra Appl 348:49-62, 2002). Similar assertions are also valid for the block numerical range of positive operator

Image Quality Dependence on Partial Coherence in a Projection Printer

A study has been made of the printed images from a projection printer whose light source can be varied to provide illumination of various levels of partial coherence. The coherence interval for five light source configurations was measured with a shearing interferometer at the object plane of the printer. Many test images were made with the printer for each of the five degrees of partial coherence and results showing image quality as a function of coherence interval have been reported. It was found that with an 11µm coherence interval the image forming characteristics were typical of an incoherent instrument and could be adequately explained by a linear transfer function. An increasing departure from linearity was seen as the coherence interval increased to 71µm. This could be best seen as an increase in ringing around edge images and emphasized high frequencies in sine wave images. For coherence intervals greater than 71µm few changes occurred in the image microstructure indicating that the printing characteristics are essentially those of a coherent system. Tri-bar resolving power showed a factor of two drop from the incoherent to the coherent imaging condition. Image microstructure effecting the macro tone reproduction was observed and concluded to be an example of the half tone effect

Labour Market Exit and Social Stratification in Western Europe: The Effects of Social Class and Gender on the Timing of Retirement

This paper analyses social variability in retirement timing. It draws on a social stratification perspective, which arguably provides a richer theoretical framework than one-dimensional pull or push approaches. The first objective is to establish how class membership influences both the timing of retirement as well as the degree of accessibility to different pathways to retirement. The second objective is to elucidate the interplay of gender and class in work-exit dynamics. The empirical analysis uses data from the Survey of Health, Ageing and Retirement in Europe (SHARE) to estimate a series of event-history models for a sample of respondents from 11 Western European countries. The results show that social class exerts a strong influence on retirement processes, over and beyond other socio-economic characteristics, and especially on the risk of involuntary retirement. Employment constraints (push factors) and economic incentives (pull factors) affect workers in different class positions in markedly different ways. While there exist significant gender differences in retirement behaviour, these appear to be largely driven by women’s lower class positions. The article concludes that ill health and unemployment remain heavy obstacles to prolonging working life in contemporary Western Europe

Transformaciones en el comportamiento en función del género en la vejez : el caso de las relaciones familiares actuales entre abuelas, abuelos y nietas y nietos

Esta exposición suscita la problemática de las transformaciones de las relaciones de género en la vejez a través de una investigación reciente de las relaciones familiares actuales entre abuelas, abuelos, nietas y nietos. Se aportan unos primeros datos que muestran sobre todo un cambio en las tareas y funciones tradicionales del cuidado que son asumidas cada vez más por los varones en la vejez.This exposition tries the theme of the transformation on gender relationship in aging. It starts from a recently research about family relationships between grandmothers, grandfathers and young boys and girls. The research data seems changing process in the traditional tasks and functions of nursing assumed by grandfathers

Changes and continuities in the women. A sociological analysis of Mercedes Alcañiz Moscardó. Diverse theoretical visions from the classical figures to Pierre Bourdieu

[Abstract] This text deals with contributing a few reflections about the book of Mercedes Alcañiz Moscardó: "Changes and continuities in the women”, in which the authoress attacks a meticulous analysis of the situation of the women from an epistemological-sociological point of view. As regards this topic the mentioned sociologist defends the thesis of a change of the classic epistemological-androcentric position in the contemporary sociology. In this frame it is deepened singularly in the theoretical vision that Pierre Bourdieu argues in its work: "The masculine domination” and in the meaning of the feminist thought, of the movement for the rights of the women and of the researches and public politics of women and gender.[Resumen] Este texto se ocupa de aportar unas reflexiones acerca de las obra de Mercedes Alcañiz Moscardó: “Cambios y continuidades en las mujeres”, en la cual la autora acomete un minucioso análisis de la situación de las mujeres desde una óptica epistemológico-sociológica. En relación con este tema la citada socióloga defiende la tesis de un cambio de la postura epistemológico-androcéntrica clásica en la sociología contemporánea. En este marco se ahonda singularmente en la visión teórica que argumenta Pierre Bourdieu en su obra: “La dominación masculina” y en el significado del pensamiento feminista, del movimiento por los derechos de las mujeres y de las investigaciones y políticas públicas de las mujeres y del género

An experimental and theoretical investigation of particle–wall impacts in a T-junction

Understanding the behaviour of particles entrained in a fluid flow upon changes in flow direction is crucial in problems where particle inertia is important, such as the erosion process in pipe bends.We present results on the impact of particles in a T-shaped channel in the laminar-turbulent transitional regime. The impacting event for a given system is described in terms of the Reynolds number and the particle Stokes number. Experimental results for the impact are compared with the trajectories predicted by theoretical particle tracing models for a range of configurations to determine the role of the viscous boundary layer in retarding the particles and reducing the rate of collision with the substrate. In particular a 2D model based on a stagnation point flow is used together with 3D numerical simulations. We show how the simple 2D model provides a tractable way of understanding the general collision behaviour, while more advanced 3D simulation can be helpful in understanding the details of the flow