Patterns of co‑occurrence and interactions between age classes of the common triplefin, Forsterygion lapillum

Many marine organisms have pelagic larval stages that settle into benthic habitats occupied by older individuals; however, a mechanistic understanding of inter cohort interactions remains elusive for most species. Patterns of spatial covariation in the densities of juvenile and adult age classes of a small temperate reef fish, the common triplefin (Forsterygion lapillum), were evaluated during the recruitment season (Feb–Mar, 2011) in Wellington, New Zealand (41°17′S, 174°46′E). The relationship between juvenile and adult density among sites was best approximated by a dome-shaped curve, with a negative correlation between densities of juveniles and adults at higher adult densities. The curve shape was temporally variable, but was unaffected by settlement habitat type (algal species). A laboratory experiment using a “multiple-predator effects”design tested the hypothesis that increased settler mortality in the presence of adults (via enhanced predation risk or cannibalism) contributed to the observed negative relationship between juveniles and adults. Settler mortality did not differ between controls and treatments that contained either one (p = 0.08) or two (p = 0.09) adults. However, post hoca analyses revealed a significant positive correlation between the mean length of juveniles used in experimental trials and survival of juveniles in these treatments, suggesting that smaller juveniles may be vulnerable to cannibalism. There was no evidence for risk enhancement or predator interference when adults were present alongside a hetero specific predator (F. varium). These results highlight the complex nature of intercohort relationships in shaping recruitment patterns and add to the growing body of literature recognizing the importance of age class interactions.

Perceptions of the common good in planning

There has been plenty of debate in the academic literature about the nature of the common good or public interest in planning. There is a recognition that the idea is one that is extremely difficult to isolate in practical terms; nevertheless, scholars insist that the idea ‘…remains the pivot around which debates about the nature of planning and its purposes turn’ (Campbell & Marshall, 2002, 163–64). At the point of first principles, these debates have broached political theories of the state and even philosophies of science that inform critiques of rationality, social justice and power. In the planning arena specifically, much of the scholarship has tended to focus on theorising the move from a rational comprehensive planning system in the 1960s and 1970s, to one that is now dominated by deliberative democracy in the form of collaborative planning. In theoretical terms, this debate has been framed by a movement from what are perceived as objective and elitist notions of planning practice and decision-making to ones that are considered (by some) to be ‘inter-subjective’ and non-elitist. Yet despite significant conceptual debate, only a small number of empirical studies have tackled the issue by investigating notions of the common good from the perspective of planning practitioners. What do practitioners understand by the idea of the common good in planning? Do they actively consider it when making planning decisions? Do governance/institutional barriers exist to pursuing the common good in planning? In this paper, these sorts of questions are addressed using the case of Ireland. The methodology consists of a series of semi-structured qualitative interviews with 20 urban planners working across four planning authorities within the Greater Dublin Area, Ireland. The findings show that the most frequently cited definition of the common good is balancing different competing interests and avoiding/minimising the negative effects of development. The results show that practitioner views of the common good are far removed from the lofty ideals of planning theory and reflect the ideological shift of planners within an institution that has been heavily neoliberalised since the 1970s.

An investigation of the changes in the natural frequency of a Pile affected by Scour

Scour around bridge foundations is one of the leading causes of bridge failure. Up until recently, the monitoring of this phenomenon was primarily based around using underwater instrumentation to monitor the progression of scour holes as they develop around foundation systems. Vibration-based damage detection techniques have been used to detect damage in bridge beams. The application of these vibration based methods to the detection of scour has come to the fore in research in recent years. This paper examines the effect that scour has on the frequency response of a driven pile foundation system, similar to those used to support road and rail bridges. The effect of scour on the vibration characteristics of the pile is examined using laboratory and field testing. It is clear that there is a very clear reduction in the natural frequency of the pile as the severity of scour increases. It is shown that by combining state-of-the-art geotechnical techniques with relatively simple finite element modelling approaches, it is possible to accurately predict the natural frequency of the pile for a given scour depth. Therefore, the paper proposes a method that would allow the estimation of scour depth for a given observed pile frequency.

Theoretical investigation of the use of a moving vehicle to identify bridge dynamic parameters

Pavements and bridges are subject to a continuous degradation due to traffic aggressiveness, ageing and environmental factors. A rational transport policy requires the monitoring of this transport infrastructure in order to provide adequate maintenance and guarantee the required levels of transport service and safety. This paper investigates the use of an instrumented vehicle fitted with accelerometers on its axles to monitor the dynamics of bridges. A simplified quarter carbridge interaction model is used in theoretical simulations and the natural frequency of the bridge is extracted from the spectra of the vehicle accelerations. The accuracy is better at lower speeds and for smooth road profiles. The structural damping of the bridge was also monitored for smooth and rough road profiles. The magnitude of peaks in the power spectral density of the vehicle accelerations decreased with increasing bridge damping and this decrease was easier to detect the smoother the road profile.

Dimensionality, Reliability and Validity of the InterRAI Depression Rating Scale in a Canadian Palliative Care Population

A reliable and valid instrument is needed to screen for depression in palliative patients. The interRAI Depression Rating Scale (DRS) is based on seven items in the interRAI Palliative Care instrument. This study is the first to explore the dimensionality, reliability and validity of the DRS in a palliative population. Palliative home care patients (n = 5,175) residing in Ontario (Canada) were assessed with the interRAI Palliative Care instrument. Exploratory factor analysis and Mokken scale analysis were used to identify candidate conceptual models and evaluate scale homogeneity/performance. Confirmatory factor analysis compared models using standard goodness-of-fit indices. Convergent and divergent validity were investigated by examining polychoric correlations between the DRS and other items. The “known groups” test determined if the DRS meaningfully distinguished among client subgroups. The non-hierarchical two factor model showed acceptable fit with the data, and ordinal alpha coefficients of 0.83 and 0.82 were observed for the two DRS subscales. Omega hierarchical (ωh) was 0.78 for the bifactor model, with the general factor explaining three quarters of the common variance. Despite the multidimensionality evident in the factor analyses, bifactor modelling and the Mokken homogeneity coefficient (0.34) suggest that the DRS is a coherent scale that captures important information on sub-constructs of depression (e.g., somatic symptoms). Higher correlations were seen between the DRS and mood and psychosocial well-being items, and lower correlations with functional status and demographic variables. The DRS distinguished in the expected manner for known risk factors (e.g., social support, pain). The results suggest that the DRS is primarily unidimensional and reliable for use in screening for depression in palliative care patients.

The Distribution and Adoption of the Byre-house (Longhouse) in Late Medieval Britain

It has long been recognized that the byre-house or longhouse, in which animals and humans lived in the same building and with direct contact, was a distinctive building plan. Earlier interpretations have seen it as a ubiquitous house type found throughout Britain, but gradually replaced by separate buildings for keeping animals and accommodating humans. More recent work has suggested that it was a regional variant of the common late medieval domestic plan. The use of this building type was restricted to parts of Wales, and northern and western areas of England. It is argued that the introduction of the byre-house occurs mainly in the thirteenth century as part of a wider trend to provide accommodation for livestock during the winter months. The byre-house was a one response to this need, and its adoption was not due to climatic or geographical factors. Instead, it is interpreted as reflecting localized cultural attitudes to the relationship between humans and animals.

The uncritical realism of realist evaluation

This article is a response to Ray Pawson’s critique of critical realism, the philosophy of science elaborated by Roy Bhaskar. I argue with Pawson’s interpretation of critical realism’s positions on both natural and social science and his charges concerning its totalizing ontology, its arrogant epistemology and its naive methodology. The differences between critical realism and realist evaluation are not as significant as Pawson contends. The main differences between the two realisms lie in their approaches to the relationship between social structures and human agency, and between facts and values. I argue that evaluation scientists need to clearly distinguish structure and agency. They should also make their values explicit. The uncritical approach of realist evaluation, combined with its underplaying of the importance of agency, leaves it open to implication in the abuses of bureaucratic instrumentalism.