Urban impacts on tropical island streams: Some key aspects influencing ecosystem response

Improving our understanding of the impacts of urbanization on tropical island streams is critical as urbanization becomes a dominant feature in tropical areas. Although the ??urban stream syndrome?? has been successful in summarizing urban impacts on streams, the response of some island streams is different to that expected. Here we review available information on urban impacts to tropical island streams and describe unique responses to urbanization. We identified three key aspects that play particularly important or unique roles in determining tropical-island stream integrity: biotic response to water pollution, movement barriers along the stream network, and altered geomorphology that results in habitat loss. As expected, water pollution negatively impacts stream ecosystems in tropical islands and in some regions impacts can be severe, as untreated wastewaters are directly discharged into streams. While aquatic insects show the expected responses to pollution, other native fauna (e.g., shrimps and fishes) appear to be less impacted by moderate levels of pollution. Movement barriers along the stream network are especially important as much of the tropical island fauna have diadromous (either amphidromous or catadromous) life histories. Most native freshwater mollusks, shrimps, and fishes inhabiting tropical islands are diadromous and depend on unimpeded connections between freshwater and marine environments to complete their life cycles. The presence of these species in urban streams is best explained by longitudinal connectivity rather than by the degree of urban impact. Finally, in streams that remain connected to marine environments, the presence of native shrimps and fishes is strongly related to the physical habitat. Fish assemblages in channelized and severely altered stream reaches are almost completely devoid of native fauna and tend to be dominated by non-native species. In contrast, relatively diverse shrimp and fish assemblages can be found in reaches that retain their physical habitat complexity, even when they are impacted by urbanization. Our understanding of urban impacts on tropical island streams remains limited. However, the identification of key aspects can help us better understand urban impacts on streams in tropical islands, and best focus our management and research efforts to protect these unique ecosystems.     

A nonparametric bayesian approach to analysis of drug dependence data

In this paper, a nonparametric Bayesian approach to the analysis of binary response data is considered. Using a Dirichlet process prior, and squared error loss, the Bayes estimators of response probabilities are obtained. Finally, the results obtained are employed to analyze the ARC 090 Trial data.     

Ensuring Parliamentary Gender Equality Through a New Zipper Method: An Application to Finland

Gender equality constitutes a crucial objective for a successful societal development. Although research has found that the differences are shrinking, parliamentary composition is not gender balanced in most areas of the world. Henceforth, recent literature has undertaken important efforts aimed at developing different initiatives to promote parity in democratic parliaments, especially through the use of quota systems. Prior initiatives, although leading to an improvement of gender parity, do not manage to ensure an optimal gender-egalitarian parliamentary composition. Thus, this paper presents a method to organize closed and blocked lists of candidates that guarantees the achievement of gender-balanced representation in parliamentary elections. Specifically, parity is sought globally, in each party and also in each electoral constituency. Furthermore, the method is applied to the elections held over the last two decades in Finland. Results reveal that parity in gender representation increases at global, party, and constituency levels throughout all the parliamentary elections in Finland, even approaching optimal numerical parity (i.e. 50 % for each gender) in most of the cases.     

Where Does it Begin? A Comparative Perspective on the Professional Preferences of First-year Social Work Students

Correspondence to Dr John Gal, Paul Baerwald School of Social Work, The Hebrew University, Mt Scopus, Jerusalem 91905, Israel. Summary The goal of this paper is to contribute to a better understandingof international social work by examining the professional preferencesof students at the beginning of the social work training processin the United States, Great Britain and Israel. The study, uponwhich the paper is based, examined the preferences of the studentswith regard client groups, social services, types of sectorsand of practices, and sought to identify the similarities andthe differences between these preferences in different countries.The findings indicate that the students from the United Statesand Israeli universities prefer to work with social groups andto be employed in services, that can be defined as "less stigmatic",while these trends were not identifiable in the case of theBritish students. They expressed a greater readiness to workwith more needy social groups and to find employment in thestate sector. By contrast, the students in all the universitiesstudied expressed a similar unwillingness to work the unemployed,the chronically ill and to find employment in old-aged homes.In addition, casework with individuals was the most preferredtype of social work practice. Clearly, the findings indicatethat the preferences of students in different countries reflectvariations in the nature of social work in each of the specificnational settings.     

Engaging young people in science education through socioscientific issues of biosecurity

ABSTRACT

The biosecurity system is extremely important to New Zealand because the economy is based largely on exporting products derived from primary industry practices. Recent developments in trade practices such as online trade have put the biosecurity system in New Zealand under further strain. In light of this, engaging young people to support biosecurity initiatives is crucial. A qualitative approach using the interpretive mode of inquiry was used to investigate the message young people got out of biosecurity educational material in the public. One hundred and seventy-one young people completed a questionnaire that consisted of Likert-scale type questions and open-ended questions that focused on getting young people’s understanding of biosecurity related educational material. The findings show that young people emotionally connected with the biosecurity educational material, but were unable to get the biosecurity message. Building prior knowledge about biosecurity through teaching and learning is recommended.     

Weighted bivariate logarithmic series distributions

In this paper, we are interested in the weighted distributions of a bivariate three parameter logarithmic series distribution studied by Kocherlakota and Kocherlakota (1990). The weighted versions of the model are derived with weight W(x,y) = x^[r] y^[s]. Explicit expressions for the probability mass function and probability generating functions are derived in the case r = s = l. The marginal and conditional distributions are derived in the general case. The maximum likelihood estimation of the parameters, in both two parameter and three parameter cases, is studied. A procedure for computer generation of bivariate data from a discrete distribution is described. This enables us to present two examples, in order to illustrate the methods developed, for finding the maximum likelihood estimates.     

Nonparametric bayes estimation of the survival function from a record of failures and follow-ups

In some observational studies, we have random censoring model. However, the data available may be partially observable censored data consisting of the observed failure times and only those nonfailure times which are subject to follow-up. Suzuki (1985) discussed the problem of nonparametric estimation of the survival function from such partially observable censored data. In this article, we derive a nonparametric Bayes estimator of the survival function for such data of failures and follow-ups under a Dirichlet process prior and squared error loss. The limiting properties such as the mean square consistency, weak convergence and strong consistency of the Bayes estimator are studied. Finally, the procedures developed are illustrated by means of an example.     

Goodness‐of‐fit tests for parametric models based on biased samples

The authors study the problem of checking the adequacy of a parametric model for a distribution using several possibly censored weight biased samples. They discuss identifiability problems related to the underlying distribution and the distributions of the biased samples. They propose a test statistic based on the supremum of the weighted aggregated martingale residual processes from a number of such samples. Both numerical and graphical procedures are discussed, which the authors apply to do model checking for oil exploration drilling data.     

How Co-operative is Co-operative Purchasing in Smaller Firms?: Evidence from UK Engineering SMEs

Most SMEs do not try to engage in co-operative purchasing arrangements, and even those that do don’t handle them very well. Examining a sample of SME engineering firms from the UK Midlands for signs of more advanced practice, the authors identify three types of behaviour: firms with deliberate strategies (where co-operative purchasing is a consciously-designed and long-term part of management policy); firms with close ties with their suppliers but which still operate fundamentally adversarial policies (where, despite some development of practice, defensive, short-term and ‘low-trust’ attitudes still predominate) and those whose strategies, maybe of long standing, ‘just happened’ and are described as still emergent. The article analyses these positions to yield lessons for managers, recognising that, as firms grow, emergent strategies will need replacing with something more codified.