Ageing in the LHCb outer tracker: Aromatic hydrocarbons and wire cleaning

The LHCb Outer Tracker straw tubes have shown to suffer from gain loss after irradiation in the laboratory at moderate intensities. Under irradiation an insulating layer is formed on the anode wire. The ageing is caused by contamination of the counting gas due to outgassing of the plastifier di-isopropyl-naphthalene in araldite AY103-1 used at construction. This paper presents irradiation results with and without the plastifier, together with the mass spectra of the glue samples. In addition, the effects of wire heating and large currents are presented.     

Effects of constructing versus playing an educational game on student motivation and deep learning strategy use

In this study the effects of two different interactive learning tasks, in which simple games were included were described with respect to student motivation and deep strategy use. The research involved 235 students from four elementary schools in The Netherlands. One group of students (N = 128) constructed their own memory ‘drag and drop’ game, whereas the other group (N = 107) played an existing ‘drag and drop’ memory game. Analyses of covariance demonstrated a significant difference between the two conditions both on intrinsic motivation and deep strategy use. The large effect sizes for both motivation and deep strategy use were in favour of the construction condition. The results suggest that constructing a game might be a better way to enhance student motivation and deep learning than playing an existing game. Despite the promising results, the low level of complexity of the games used is a study limitation.     

Leisurely Lesbians in a Small City in South Africa

Over the past two decades, particularly in post-industrial societies, the geographies of gay men’s and, to a lesser extent, gay women’s lives have received considerable research attention. A central research interest has been the mapping of gay geographies of leisure. There are, however, fewer studies in the academic record about gay leisure geographies in the developing world context, particularly in Africa. This investigation aims to address an aspect of this investigatory oversight by looking through the lens of white gay women in the city of Bloemfontein, South Africa. The study maps white gay women’s leisure-seeking and positions their (sexual) desire(s) relative to other homosexual and heterosexual leisure geographies. A highly complex and contradictory set of spatial and temporal patterns and practices emerge in which desire and repulsion are often in close proximity located in a number of leisure, retail, work, and private spaces. In addition, these spaces are inhabited by a range of different identity cohorts according to gender, gender performativity, class, and race.     

Development of attitude strength over the life cycle: surge and decline

This article explores the relation of age to manifestations and antecedents of attitude strength. Three studies demonstrate that susceptibility to attitude change is greater during early and late adulthood than during middle adulthood. Three additional studies demonstrate that attitude importance, certainty, and perceived quantity of attitude-relevant knowledge are greater in middle adulthood than during early or late adulthood. These antecedents may therefore explain life cycle shifts in susceptibility to change. Susceptibility to change, importance, certainty, and perceived knowledge differ from one another in terms of their correlations with education, gender, and race, challenging the notion that attitude strength is a unitary construct. Evidence that people incorrectly believe that susceptibility to change declines steadily over the life course reinforces the distinction between operative and meta-attitudinal measures of attitude strength.     

The early phase of engraftment after murine blood cell transplantation is mediated by hematopoietic stem cells

Blood cells transplantation is largely replacing bone marrow transplantation because engraftment is more rapid. This accelerated engraftment is thought to be mediated by relatively mature committed hematopoietic progenitor cells. Herein, we have used a modified rhodamine (Rho) staining procedure to identify and purify Rho+/++ (dull/bright) and Rho- (negative) subpopulations of hematopoietic progenitor cells in murine cytokine-mobilized blood. The Rho+/++ cell population contained > 99% of committed progenitor cells with in vitro colony-forming ability. The Rho- cell population contained the majority of hematopoietic stem cells with in vivo marrow repopulating ability. The rate of hematopoietic reconstitution was identical in recipients of grafts containing only purified Rho- stem cells or purified Rho- stem cells in combination with large numbers of Rho+/++ committed progenitor cells. In contrast, transplantation of 3-fold more hematopoietic stem cells resulted in accelerated reconstitution, indicating that the reconstitution rate was determined by the absolute numbers of Rho- stem cells in the graft. In addition, we observed a 5- to 8-fold reduced frequency of the subset of hematopoietic stem cells with long-term repopulating ability in cytokine-mobilized blood in comparison to steady-state bone marrow. Our results indicate that hematopoietic stem cells and not committed progenitor cells mediate early hematopoietic reconstitution after blood cell transplantation and that relative to bone marrow, the frequency of stem cells with long-term repopulating ability is reduced in mobilized blood.     

Energy requirements for growth in relation to sexual size dimorphism in marsh harrier Circus aeruginosus nestlings

Food consumption was measured in six female and seven male hand-raised marsh harrier (Circus aeruginosus) nestlings. Females consumed on average 4,321 g and males consumed 3,571 g of food during the nestling stage from 0 to 36 d. Total consumption until 56 d was 6,960 g and 5,822 g for females and males, respectively. On the basis of Fisher's sex ratio theory, this food intake ratio of 0.46 (intake male/[intake male + female]) would explain the observed male-biased fledging sex ratio of 55% males in marsh harrier broods. Growth, gross energy intake, and metabolizable energy intake were measured, along with metabolism of the nestlings, enabling us to determine energy allocation. The assimilation quotient (Q = 0.72) did not differ systematically between the sexes. Differences in metabolic rates between males and females at 15 and 30 d of age were fully attributable to the difference in body mass. Sexual size dimorphism in marsh harriers (female body mass around 60 d of age is 1.28 times greater than male mass) did not fully explain the difference in food intake between male and female nestlings: an analysis of energy requirements for growth and body mass in 16 avian species shows that energy intake was less than proportional to the average body mass at release. The data presented in this study are in agreement with Fisher's theory of inverse proportionality between the sex-specific ratios of energy requirements for growth and of offspring numbers in the marsh harrier population.