Testing the effect of conspecific reproductive success on dispersal and recruitment decisions in a colonial bird: Design issues

Factors affecting dispersal and recruitment in animal populations will play a prominent role in the dynamics of populations. This is particularly the case for subdivided populations where the dispersal of individuals among patches may lead to local extinction and 'rescue effects'. A long-term observational study carried out in Brittany, France, and involving colour-ringed Black-legged Kittiwakes (Rissa tridactyla) suggested that the reproductive success of conspecifics (or some social correlate) could be one important factor likely to affect dispersal and recruitment. By dispersing from patches where the local reproductive success was low and recruiting to patches where the local reproductive success was high, individual birds could track spatio-temporal variations in the quality of breeding patches (the quality of breeding patches can be affected by different factors, such as food availability, the presence of predators or ectoparasites, which can vary in space and time at different scales). Such an observational study may nevertheless have confounded the role of conspecific reproductive success with the effect of a correlated factor (e.g. the local activities of a predator). In other words, individuals may have been influenced directly by the factor responsible for the low local reproductive success or indirectly by the low success of their neighbours. Thus, an experimental approach was needed to address this question. Estimates of demographic parameters (other than reproductive success) and studies of the response of marked individuals to changes in their environment usually face problems associated with variability in the probability of detecting individuals and with nonindependence among events occurring on a local scale. Further, very few studies on dispersal have attempted to address the causal nature of relationships by experimentally manipulating factors. Here we present an experiment designed to test for an effect of local reproductive success of conspecifics on behavioural decisions of individuals regarding dispersal and recruitment. The experiment was carried out on Kittiwakes within a large seabird colony in northern Norway. It involved (i) the colour banding of several hundreds of birds; (ii) the manipulation (increase/decrease) of the local reproductive success of breeding groups on cliffpatches; and (iii) the detailed survey of attendance and activities of birds on these patches. It also involved the manipulation of the nest content of marked individuals breeding within these patches (individuals failing at the egg stage were expected to respond in terms of dispersal to the success of their neighbours). This allowed us to test whether a lower local reproductive success would lower (1) the attendance of breeders at the end of the breeding season; (2) the presence of prospecting birds; and (3) the proportion of failed breeders that came back to breed on the same patch the year after. In this paper, we discuss how we dealt with (I) the use of return rates to infer differences in dispersal rates; (II) the trade-off between sample sizes and local treatment levels; and (III) potential differences in detection probabilities among locations. We also present some results to illustrate the design and implementation of the experiment.     

Implications of survey design for generalized regression estimation of linear functions

The paper presents a general randomization theory approach to point and interval estimation of Q linear functions T_q = Σ^N₁c_kqY_k(q = 1,…,Q), where Y₁,…,Y_N are values of a variable of interest Y in a finite population. Such linear functions include population and domain means and totals, population regression coefficients, etc. We assume that some auxiliary information can be exploited. This suggests the generalized regression technique based on the fit of a linear model, whereby is created approximately design unbiased estimators T?_q. The paper focuses on estimation of the variance-covariance matrix of the T?_q for single stage and two stage designs. Two techniques based on Taylor expansions are compared. Results of Monte-Carlo experiments (not reported here) show that the coverage properties are good of normal-theory confidence intervals flowing from one or the other variance estimate.     

The Role of Joint Attention in Later Development Among Preterm Children: Linkages Between Early and Middle Childhood

Joint attention is a hallmark of human cognition. It refers to the capacity to coordinate attention to objects and events with attention to other people. Infants display considerable individual differences in this capacity. This longitudinal study of 13‐month‐old preterms was conducted to examine the hypothesis that two different types of joint‐attention skills assessed in an infant–tester paradigm are related to verbal and nonverbal IQ measures through middle childhood. Data are reported separately for the children's tendency to initiate such skills and to respond to an experimenter's offers to share in such behaviours. The results provide support for the hypothesis that the initiation of joint attention makes a unique contribution to later nonverbal IQ apart from variance associated with biomedical risk status and infant development. The results of this study have implications for the conceptualisation of joint‐attention skills, as well as for understanding the relation between joint attention and later cognition.     

HIV-infected African families living in Stockholm/Sweden: their social network, level of disclosure and knowledge about HIV

Most HIV-infected parents in Stockholm are of African origin. Many of them have several children, but their social network is often limited. This article looks at the networks of these families in relation to different aspects of HIV in order to improve the support strategies. The theoretical basis of the study rests on network and ecological systems theory. The social networks of the families in the study were found to be generally of similar size in Sweden and in the home country. However, of 47 HIV-infected parents only 21 (45%) had disclosed their HIV status to friends and relatives in Sweden. The lack of a social network was especially prominent among single women. Contact with counsellors at the HIV clinic and the social welfare office increased the probability of disclosure about HIV infection. The lack of knowledge about HIV transmission and about whom to inform about the infection stresses the importance of improved counselling. The support strategies aimed at broadening the patient's network and breaking their isolation need to be continued and strengthened.     

The Role of Forgiveness in Divorce Adjustment and the Impact of Affect

The role of forgiveness and affect was investigated in relation to divorce adjustment. Ninety-one participants separated from their ex-spouse less than 30 months completed a background questionnaire, the Enright Forgiveness Inventory (EFI), the Self Forgiveness Scale (SFS), the Center for Epidemiological Studies–Depression Inventory (CES–D), the Spielberger State–Trait Anger Inventory (STAXI–2), and the Fisher Divorce Adjustment Scale (FDAS). There were significant relationships between depression and the capacity to forgive and between being in an angry feeling state and harboring a lack of forgiveness toward the ex-spouse. The relationship that emerged as the most powerful was that between trait anger and lack of self-forgiveness. Forgiveness intervention that occurs early in the divorce adjustment process is implicated, particularly in relation to the self.     

旅游研究中的“真实性”:纷争之后

真实性的内涵如此多义,以致莱辛格与斯坦纳提出应摒弃该概念。然而自麦坎内尔将真实性引入社会学研究的30年来,相关研究蔚为大观,学界就客观真实性、主观真实性与建构真实性展开系列辩论与研究;另一方面,实践中的真实性样态层出不穷,譬如真实的复制与真正的赝品、生命历程中的真实性或人造景观的真实性。在后真实时代,旅游客体的真实性主要由旅游体验来裁决。     

Treatment‐as‐usual in effectiveness studies: What is it and does it matter?

Andrée Löfholm C, Brännström L, Olsson M, Hansson K. Treatment‐as‐usual in effectiveness studies: What is it and does it matter? A hallmark of an evidence‐based practice (EBP) is the systematic appraisal of research related to the effectiveness of interventions. This study addressed the issue of interpreting results from effectiveness studies that use treatment‐as‐usual (TAU) as a comparator. Using randomised controlled studies that evaluate the effectiveness of multisystemic therapy as an illustrative example, we show that TAU includes a wide variety of treatment alternatives. Estimated treatment effects on recidivism suggest that TAU seems to contain a greater variation in underlying risk than experimental conditions, supporting the hypothesis that the content of TAU could affect outcomes. Implications for the realisation of an EBP are discussed.     

On the Differential Attachments of Migrants from Central and Eastern Europe: A Typology of Labour Migration

In this article we develop an empirically grounded typology of labour migration patterns among migrants from Central and Eastern Europe, based on two dimensions: attachment to the destination country and attachment to the country of origin. We conducted a survey (N=654) among labour migrants in the Netherlands from Poland, Bulgaria and Romania. We found four migration patterns in our data: (i) circular migrants (mostly seasonal workers) with weak attachments to the country of destination, (ii) bi-nationals with strong attachments to both the home country and that of destination, (iii) footloose migrants with weak attachments to both the home and the destination country, and (iv) settlers with weak attachments to the home country. Our findings demonstrate the relevance to the debate on transnationalism and integration of distinguishing different migration patterns. Successful integration in Dutch society can go hand-in-hand with ‘strong’ as well as with ‘weak’ forms of transnationalism. The bi-national pattern shows a tendency to strong transnationalism, while the settlement pattern demonstrates less transnational involvement with the country of origin.     

From exile to post-exile: the diasporisation of Swedish Chileans in historical contexts

The main focus of this article is how a set of practices revolve around the formation of an imagined community in dispersion – diasporisation. The study discusses the case of the Chilean diaspora in Sweden and its transformation from an exile context to a post-exile context facing a drastically altered historical situation. This transformation is analysed as a matter of agency where practices are framed differently as a response to the demand perceived in the context. The outcome of this argument speaks in favour of a diaspora concept that focuses on practices and how these are framed in order to mobilise a putative dispersed population.