Salinization alters ecosystem structure in urban stormwater detention ponds

Stormwater ponds now comprise a significant portion of standing water in urban areas. These ponds act to sequester excess run-off and pollutants, such as road salt deicers. While these man-made ponds are not intended to serve as freshwater ecosystems, it is becoming clear that they do provide habitat for many organisms, but we know little of their ecosystem structure, function and interactions with pollutants. From April through June 2009, we surveyed 8 stormwater ponds in the Red Run Watershed, Baltimore County, Maryland, USA to describe patterns in aquatic food webs associated with a gradient in road salt inputs. Periphyton, phytoplankton and zooplankton samples were collected from each pond every 4–6 weeks. Specific conductance, a measure of chloride salt loading, among the 8 ponds varied widely throughout the survey, ranging from 99 μS cm⁻¹ to 19,320 μS cm⁻¹. Low (average = 404 +/− 82.6 (SE) μS cm⁻¹) and medium (average = 1749 +/− 267 (SE) μS cm⁻¹) conductance ponds had lower algal biomass and higher densities of zooplankton taxa relative to high (average = 7231 +/− 2143 (SE) μS cm⁻¹) conductance ponds, which were largely devoid of all zooplankton through the end of May. The observed decline in zooplankton density along an increasing chloride gradient is consistent with experimental results of road deicer effects, suggesting algal resources are possibly freed from grazing pressure as zooplankton consumers are negatively impacted by road salt exposure. Our results highlight the potential for both direct and indirect effects of road deicers on freshwater communities.     

The role of the tutor in social work education: Building an emancipatory tutorial relationship

The role of the social work tutor and tutorial relationship has received little attention over the last decade despite the implications this has had for developing competent practitioners. It is the authors' contention that unless the tutor/tutee relationship is developed within an empowering framework, then it potentially can lead to competence being defined around an administrative and therefore limiting approach to practice. While such an approach may predominate within modern social services this does not mean that it is inevitable or unable to be challenged and changed. This paper considers one approach to developing the tutorial relationship within an empowering framework that uses the processes of the course to empower students to take greater control of their learning and builds a model for their future supervisory relationships in practice.     

Alcohol Advertising in College Newspapers: A 7-Year Follow-up

Abstract

The authors report on the frequency and nature of alcohol advertisements in a representative sample of college newspapers from 1984/85 and compare these with results of a similar study conducted 7 years earlier, in 1977/78. On average, nearly 24 column inches of space per issùe were devoted to national alcohol advertisements in 1984/85. This represents a significant decrease from an earlier period. The space devoted to national alcohol advertisements, however, still far exceeded that for comparison products (books, soft drinks). Local alcohol advertisements averaged 20 column inches per issue and were somewhat more frequent than in the previous study. The content of the advertisements differed markedly from the messages presented 7 years earlier. Although national alcohol advertisements in 1977/78 frequently ridiculed education and study, none did so in 1984/85, when appeals were to taste and product quality instead. Fantasy themes also were relatively common. Very few national alcohol advertisements featured athletes or group drinking. Sponsorship of campus activities by the alcohol industry, however, had increased since the earlier study. In contrast to national advertisements, many local advertisements consisted of inducements to drink through special offers and happy hours. Some encouraged irresponsible and heavy drinking. Interestingly, alcohol advertisements were just as frequent in papers from states with higher minimum drinking ages and were more frequent in papers from campuses with higher proportions of women students.     

Developing an empowering approach to child care teaching

This paper describes the thinking and planning involved in the teaching of a module entitled 'Working with Children, their Families and Carers', on the DipSW programme in the West of Scotland. It outlines the reasons, both educational and professional, behind the approach that was adopted and explains how a combination of problem-based learning and reflective practice enabled students to develop a clearer understanding of their professional competence.     

Therapeutic Hypothermia: Quantification of the Transition of Core Body Temperature Using the Flexible Mixture Bent‐Cable Model for Longitudinal Data

Hypothermia which is induced by reducing core body temperature is a therapeutic tool used to prevent brain damage resulting from physical trauma. However, all physiological systems begin to slow down due to hypothermia and this can result in increased risk of mortality. Therefore quantification of the transition of core body temperature to early hypothermia is of great clinical interest. Conceptually core body temperature may exhibit an either gradual or abrupt transition. Bent‐cable regression is an appealing statistical tool to model such data due to the model's flexibility and readily interpretable regression coefficients. It handles more flexibly models that traditionally have been handled by low‐order polynomial models (for gradual transition) or piecewise linear changepoint models (for abrupt change). We consider a rat model to quantify the temporal trend of core body temperature primarily to address the question: What is the critical time point associated with a breakdown in the compensatory mechanisms following the start of hypothermia therapy? To this end, we develop a Bayesian modelling framework for bent‐cable regression of longitudinal data to simultaneously account for gradual and abrupt transitions. Our analysis reveals that: (i) about 39% of rats exhibit a gradual transition in core body temperature; (ii) the critical time point is approximately the same regardless of transition type; and (iii) both transition types show a significant increase of core body temperature followed by a significant decrease.     

A competing risks derivation of a mixture model for the analysis of survival data

Boag (1949) and Berkson and Gage (1952) proposed a mixture model for the analysis of survival time data when aproportion of treated patients are cured. This paper presents a derivation of the Boag/Berkson-Gage mixture model as well as a eneralization of the model based on the theory of competing risks. The assumptions underlying the model are stated and discussed and a general likelihood function is obtained. Use of the model is illustrated ith data from the Stanford Heart Transplant Program.     

The Foster–Greer–Thorbecke (FGT) poverty measures: 25 years later

Twenty-five years ago, the FGT class of decomposable poverty measures was introduced in Foster, Greer, and Thorbecke (Econometrica 52:761–776, 1984). The present study provides a retrospective view of the FGT paper and the subsequent literature, as well as a brief discussion of future directions. We identify three categories of contributions: to measurement, to axiomatics, and to application. A representative subset of the literature generated by the FGT methodology is discussed and grouped according to this taxonomy. We show how the FGT paper has played a central role in several thriving literatures and has contributed to the design, implementation, and evaluation of prominent development programs; the breadth of its impact is evidenced by the many topics beyond poverty to which its methodology has been applied. We conclude with a selection of prospective research topics.     

Applying Cognitive Theory to Statistics Instruction

This article presents five principles of learning, derived from cognitive theory and supported by empirical results in cognitive psychology. To bridge the gap between theory and practice, each of these principles is transformed into a practical guideline and exemplified in a real teaching context. It is argued that this approach of putting cognitive theory into practice can offer several benefits to statistics education: A means for explaining and understanding why reform efforts work; a set of guidelines that can help instructors make well-informed design decisions when implementing these reforms; and a framework for generating new and effective instructional innovations.