Persistence and survival of the spider <Emphasis Type="Italic">Nephila plumipes</Emphasis> in cities: do increased prey resources drive the success of an urban exploiter?

Species that successfully inhabit urban ecosystems are rare, and urbanisation often drives localised extinctions of native species. Nonetheless, some species take advantage of the novel conditions available in cities and increase in abundance. Trends in the abundance and distribution of species in urban areas have received much attention, but the precise elements of urban ecosystems that affect the survival of urban-dwelling species are largely unknown. Animals that successfully exploit urban environments may do so because of increases in the availability of resources or habitats. Here we assess the effects of anthropogenic landscapes and prey abundance on the persistence of an orb-weaving spider, Nephila plumipes. We assessed spider persistence for six months in situ along an urban gradient in Sydney. We then transplanted spiders from a common garden into sites along the gradient, monitored their persistence in the new environment and measured a suite of environmental variables at local and landscape scales. The abundance of prey was closely linked with spider persistence, in both the survey and the transplant experiment, and was positively associated with anthropogenic habitats. The surveyed spiders survived longer when located closer to the coast and transplanted spiders persisted longer in smaller sites with more impervious surfaces and reduced vegetation cover. Our study shows that urbanisation has a strong effect on potential prey abundance and can lead to increased persistence of N. plumipes, demonstrating the broad impacts that habitat disturbance can have on the life history and trophic interactions of city-dwelling animals.     

Common urban birds continue to perceive predator calls that are overlapped by road noise

Recent studies suggest that songbird communication is negatively affected by anthropogenic noise. However, much of the current literature focuses on inter- and intra-sexual communication. Songbirds also use acoustic cues for many other functional behaviors. One example associated with fitness consequences is the identification of predatory threats through acoustic cues. To test the effect of anthropogenic noise on detection of acoustic cues, we compared the rates of seven anti-predator behavioral responses in urban dwelling songbirds foraging at bird feeders when exposed to playback of calls from predatory Cooper’s hawks under quiet conditions, and when overlapped with road noise. Only a single behavior, freeze response, decreased significantly when calls were overlapped with noise. However, freeze responses occurred in only a small percentage of playback trials, raising some question regarding the biological relevance of this observed difference. Overall, our results suggest that common urban songbirds are relatively successful at perceiving acoustic signals associated with predator presence. Whether this ability is commonplace amongst songbird species is unknown and warrants additional study. However, if this trait is not widespread, it may be an additional characteristic determining which bird species can inhabit noisy areas.

     

Assessing the contribution of fallen autumn leaves to airborne fungi in an urban environment

Urban Ecosystems - Many street trees in urban areas are deciduous and drop leaves during autumn. These leaves are a potential growing substrate for fungi, which when aerosolized and inhaled, can...     

Infant–Mother and Infant–Caregiver Emotional Relationships: Process Analyses of Interactions in Three Contemporary Childcare Arrangements

Emotional relationships in infant–mother dyads in families where mothers provided full‐time childcare were compared with those of families where mothers used in‐home childcare providers and family childcare providers (N = 245). Infant relationships with childcare providers were also studied. Emotional relationships were adequate in all three childcare arrangements, but infant–mother dyads in in‐home childcare arrangements displayed healthier emotional relationships than infant–mother dyads in mother care arrangements; no differences in the health of emotional relationships with infants emerged among the three types of childcare providers (mother care, in‐home childcare, family childcare). Infant–mother dyads in in‐home childcare arrangements also displayed healthier emotional relationships than infant–in‐home childcare caregiver dyads, but infant–mother and infant–caregiver dyads were comparable in family childcare families. Emotional relationships in infant–mother and infant–caregiver dyads were not correlated, regardless of the type of childcare.     

A CANONICAL ANALYSIS OF MANAGERIAL-ENVIRONMENTAL RELATIONSHIPS: IMPLICATIONS FOR METHODOLOGY AND POLICY*

The present study uses canonical analysis to examine the contingency model of organizations in the nursing home field. Data on environmental pressures and managerial practices relevant to the decision-making process are analyzed. Results support the theory that managerial practices are contingent on environmental pressures. The implications of these results for health-care decision makers and for future assessments of managerial-environmental relationships are discussed.     

The Impact of Learning and Labor Attrition on Worker Flexibility in Dual Resource Constrained Job Shops

This study investigates the impact of worker learning, worker flexibility, and labor attrition on the system performance of a dual resource constrained (DRC) job-shop. The effects of learning and labor attrition have not been previously addressed in DRC literature. Results from the study, consistent with previous literature, show that the greatest benefits are achieved when inter-departmental worker flexibility is incrementally introduced into the system. In addition, the learning environment, which depends on the initial processing time of jobs and the learning rates of workers, is shown to impact the acquisition of flexibility. The study also shows that the impact of labor attrition on system performance under certain shop conditions may be significant.     

A Learning Curve Analysis of Expert System Use*

In this article, we study how an expert system affects novice problem solving in a financial risk analysis domain. We demonstrate that novice performance is improved after exposure to an expert system. Further, we show that novice performance continues to improve when the system is withdrawn. By comparing learning curves for people with exposure to those without, we can assess how much the system has benefitted its users. We demonstrate a quantitative methodology to measure the increment of learning due to the use of an information technology. We also explore the issue of how expertise is transferred from the system to the user.     

Sensitivity Analysis in Linear Programming Models with Common Inputs

The importance of sensitivity analysis information in linear programming has been stressed in the management science literature for some time. Indeed, Gal [3] has devoted an entire text to just this issue. Linear programs with common inputs (cost coefficients or right-hand-side values) present a problem in that classical sensitivity analysis does not allow for the simultaneous changes required to determine the sensitivity of these models to common inputs. We first survey the approaches previously developed for simultaneous-change sensitivity analysis and cast them in the framework of the special common input case. These general techniques are compared to a simple aggregate variable technique that has not received attention in the literature.     

Mainstreaming kink: the politics of BDSM representation in U.S. popular media

This article explores nonpractitioners' understandings of and responses to the increasingly mainstream representation of BDSM in U.S. media, focusing on the film Secretary (Shainberg, 2002). Survey, focus group, and interview data indicate that popular images of SM promote the acceptance and understanding of sexual minorities through two mechanisms: acceptance via normalization, and understanding via pathologizing. Rather than challenging the privileged status of normative sexuality, these mechanisms reinforce boundaries between protected/privileged and policed/pathological sexualities. Instead of celebrating increased representation, this article argues that political energy might be directed toward the desire that the popularity of BDSM representations signifies: the desire to encounter authentic, undisciplined, and noncommodified representations that would transgress the sexual norms of American postmodern consumer culture.