Commitments in Groups and Commitments of Groups

I argue that a group can have normative commitments, and that the commitment of a group is not merely a sum or aggregate of the commitments of individual group members. I begin with a set of simple cases which illustrate two structurally different ways that group commitments can go wrong. These two kinds of potential failure correspond to two different levels of commitment: one at the individual level, owed to the other group members, and one at the group level, which the group as a single body owes either to itself or to some third party. I distinguish the content of a commitment (what must be done for the commitment to be fulfilled) from the holder of that commitment: the party to whom the content is owed. I then discuss examples which support the two-level view of group commitment and show that, even when individual-level and group-level commitments have the same content, they are understood to have different holders. Finally I return to my original cases and argue that a two-level structure of group commitment allows us to make sense of the problems that occur in them

Review on the epidemiology and dynamics of BSE epidemics

The paper describes how the comprehensive surveillance of bovine spongiform encephalopathy (BSE) and studies carried out on these data has enhanced our knowledge of the epidemiology of BSE. Around 7 000 BSE cases were detected through the screening of about 50 million cattle with rapid tests in Europe. It confirmed that the clinical surveillance had a poor capacity to detect cases, and also showed the discrepancy of this passive surveillance efficiency between regions and production types (dairy/beef). Other risk factors for BSE were being in a dairy herd (three times more than beef), having a young age at first calving (for dairy cattle), being autumn-born (dairy and beef), and being in a herd with a very high milk yield. These findings focus the risk on the feeding regimen of calves/heifers. Several epidemiological studies across countries suggest that the feedborne source related to meat and bone meal (MBM) is the only substantiated route of infection ¿ even after the feed ban ¿, while it is not possible to exclude maternal transmission or milk replacers as a source of some infections. In most European countries, the average age of the cases is increasing over time and the prevalence decreasing, which reflects the effectiveness of control measures. Consistent results on the trend of the epidemic were obtained using back-calculation modelling, the R0 approach and Age-Period-Cohort models. Furthermore, active surveillance also resulted in the finding of atypical cases. These are distinct from previously found BSE and classified in two different forms based on biochemical characteristics; their prevalence is very low (36 cases up to 1st September 2007), affected animals were old and some of them displayed clinical signs. The origin and possibility of natural transmission is unknown

Where's the harm? A social marketing approach to reframing 'problem' drinking cultures

Alcohol consumption is often linked to a broad range of social and health problems, yet alcohol also plays a fundamental role in social bonding between people. This paper considers the potential of social marketing to contribute to alcohol consumption reduction and reframe social norms that encourage 'problem' drinking. Based on qualitative research with a variety of Scottish drinkers, the paper emphasises how and why a better understanding of the culturally bound meanings of alcohol (e.g. social identity, self-concept) are of crucial importance to inform any social marketing approach to reframing excessive drinking

Varying Coefficient Tensor Models for Brain Imaging

We revisit a multidimensional varying-coefficient model (VCM), by allowing regressor coefficients to vary smoothly in more than one dimension, thereby extending the VCM of Hastie and Tibshirani. The motivating example is 3-dimensional, involving a special type of nuclear magnetic resonance measurement technique that is being used to estimate the diffusion tensor at each point in the human brain. We aim to improve the current state of the art, which is to apply a multiple regression model for each voxel separately using information from six or more volume images. We present a model, based on P-spline tensor products, to introduce spatial smoothness of the estimated diffusion tensor. Since the regression design matrix is space-invariant, a 4-dimensional tensor product model results, allowing more efficient computation with penalized array regression

Getting the Description Right

If Jane prefers a over b, and b over c, we normally expect her to prefer a over c too. Such transitivity of behavior is central to our normative assessment of the rationality of choices. However, experimental evidence shows recurring and stable violations of transitivity in choices over time. Are we ultimately incapable of satisfying our own criteria of rationality? In the present article, I shall argue against this conclusion. In ultimately choosing c rather than a, Jane might have been guided in her decision-making process by rational considerations (yet) unknown to the observer. New information or changed circumstances could have influenced the initial option c (and hence its assessment) such that it can be meaningfully refined and re-described as c*. As c* is preferred over a the transitivity of the preference ordering is preserved. Such a strategy, however, has been criticized by Paul Anand (1990). According to him, to re-describe prima facie intransitive behavior in transitive terms is necessarily ad hoc, arbitrary, and self-defeating. In the present article this conclusion is contested as Anand bases his reasoning on two questionable assumptions: a division between descriptive and normative decision theory, and observable choice being the sole criterion for describing preferences

A developmental investigation of the relationship between appraisals and peer self-esteem in children experiencing peer-aggression

Transactional models of stress and coping emphasize the role played by cognitive appraisals in determining psychological adjustment (Lazarus, 1999). This proposition has been supported by research examining young people's adjustment in relation to family conflict and break-up (Grych et al., 1992). Furthermore, this literature suggests that there is a change in the relationship between appraisals and adjustment at around 10 years of age: specificity of appraisal type (e.g. threat, blame) becomes relevant to outcome after 10 years, whereas before 10 there are either no effects of appraisal on adjustment or a diffuse effect of 'negative' appraisals more generally (Jouriles et al., 2000). However, it is currently unclear whether this developmental progression can be generalized from familial- to social-stressors experienced by children and young people. The current study therefore evaluates the model within the context of a commonly experienced social childhood stressor: peer-aggression

Space-Varying Coefficient Models for Brain Imaging

The methodological development and the application in this paper originate from diffusion tensor imaging (DTI), a powerful nuclear magnetic resonance technique enabling diagnosis and monitoring of several diseases as well as reconstruction of neural pathways. We reformulate the current analysis framework of separate voxelwise regressions as a 3d space-varying coefficient model (VCM) for the entire set of DTI images recorded on a 3d grid of voxels. Hence by allowing to borrow strength from spatially adjacent voxels, to smooth noisy observations, and to estimate diffusion tensors at any location within the brain, the three-step cascade of standard data processing is overcome simultaneously. We conceptualize two VCM variants based on B-spline basis functions: a full tensor product approach and a sequential approximation, rendering the VCM numerically and computationally feasible even for the huge dimension of the joint model in a realistic setup. A simulation study shows that both approaches outperform the standard method of voxelwise regressions with subsequent regularization. Due to major efficacy, we apply the sequential method to a clinical DTI data set and demonstrate the inherent ability of increasing the rigid grid resolution by evaluating the incorporated basis functions at intermediate points. In conclusion, the suggested fitting methods clearly improve the current state-of-the-art, but ameloriation of local adaptivity remains desirable