Introduced Mammalian Predators Induce Behavioural Changes in Parental Care in an Endemic New Zealand Bird

The introduction of predatory mammals to oceanic islands has led to the extinction of many endemic birds. Although introduced predators should favour changes that reduce predation risk in surviving bird species, the ability of island birds to respond to such novel changes remains unstudied. We tested whether novel predation risk imposed by introduced mammalian predators has altered the parental behaviour of the endemic New Zealand bellbird (Anthornis melanura). We examined parental behaviour of bellbirds at three woodland sites in New Zealand that differed in predation risk: 1) a mainland site with exotic predators present (high predation risk), 2) a mainland site with exotic predators experimentally removed (low risk recently) and, 3) an off-shore island where exotic predators were never introduced (low risk always). We also compared parental behaviour of bellbirds with two closely related Tasmanian honeyeaters (Phylidonyris spp.) that evolved with native nest predators (high risk always). Increased nest predation risk has been postulated to favour reduced parental activity, and we tested whether island bellbirds responded to variation in predation risk. We found that females spent more time on the nest per incubating bout with increased risk of predation, a strategy that minimised activity at the nest during incubation. Parental activity during the nestling period, measured as number of feeding visits/hr, also decreased with increasing nest predation risk across sites, and was lowest among the honeyeaters in Tasmania that evolved with native predators. These results demonstrate that some island birds are able to respond to increased risk of predation by novel predators in ways that appear adaptive. We suggest that conservation efforts may be more effective if they take advantage of the ability of island birds to respond to novel predators, especially when the elimination of exotic predators is not possible

Pre-agricultural plant management in the uplands of the central Zagros: the archaeobotanical evidence from Sheikh-e Abad

Prior to the emergence of agriculture in southwest Asia, sedentarising human communities were experimenting with a diverse range of wild plant species over a prolonged period. In some cases, this involved the cultivation of species that would go on to be domesticated and form the foundation of future agricultural economies. However, many forms of plant use did not follow this trajectory, and in multiple places farming was only taken up later as an established ‘package’. In this paper, we present new archaeobotanical evidence from the Early Neolithic site of Sheikh-e Abad in the central Zagros of western Iran. Sheikh-e Abad is unique in being the only settlement known to date within southwest Asia that lies at an altitude above 1000m and which has occupation spanning the agricultural transition. Thus, it provides a rare opportunity to examine pre-agricultural plant management strategies in an upland zone. Our analyses of the plant remains from Sheikh-e Abad suggest that from its earliest occupation inhabitants were unconsciously ‘auditioning’ a suite of locally available wild grasses which ultimately were never domesticated. We discuss the possible reasons for this from a socio-ecological perspective, considering both the biology and ecology of the plant species in question, as well as the ways in which they were potentially managed

Assessing and improving the quality of modeling : a series of empirical studies about the UML

Assessing and Improving the Quality of Modeling A Series of Empirical Studies about the UML This thesis addresses the assessment and improvement of the quality of modeling in software engineering. In particular, we focus on the Unified Modeling Language (UML), which is the de facto standard in industrial practice. The language is used for a wide variety of purposes, such as specification, maintenance, comprehension, communication, test case generation, and code generation. The UML has some inherent characteristics, that cause risks to the quality of UML modeling. The characteristics of interest in this thesis are its lack of a formal semantics, its multidiagram architecture, and its large complexity. These characteristics can lead to quality problems with respect to correctness, comprehensibility, consistency, nonredundancy, completeness, or unambiguity. In this thesis we assess the quality of modeling in practice, and we provide and evaluate techniques to improve the quality of modeling. We conducted three large-scale experiments with 365 participants in total. Additionally a series of industrial case studies was conducted. To define the notion of quality that is used throughout this thesis, we present a framework that is based on existing work. The framework decomposes quality of models into the following quality notions: system, semantic, syntactic, pragmatic, social, and communicative quality, and correspondence between the model and the implementation. We use these notions throughout the thesis to denote which aspect of quality is addressed in each of the presented studies. Additionally, we propose a quality model for UML modeling. The purpose of the quality model is to support developers in selecting metrics and rules to analyze the quality of a model with respect to a particular purpose of modeling. We report on a series of industrial case studies. We conducted the case studies to assess the quality of UML models in practice. The results of the case studies reveal the frequency of occurrence of defect types in modeling. This knowledge can be used to focus quality assurance techniques on common quality problems. Through the case studies we discovered defects in UML models. We conducted an experiment to study the effects of several of the discovered defect types. The results of the experiment show that defects often remain undetected by developers. Furthermore, defects cause a variety of different interpretations of the model amongst developers and, hence, lead to misinterpretations and miscommunication. An additional result of the experiment is a classification of defect types with respect to their likelihood of non-detection and misinterpretation. This objective classification can be used to prioritize defects, such that removal effort is assigned to the most severe defects first. As a preventive quality assurance technique we propose modeling conventions, similar to coding conventions for programming. Based on a literature review we provide a classification of modeling conventions. We report on an exploratory experiment that studied the effectiveness of modeling conventions with respect to defect prevention and the extra effort entailed by modeling conventions. The results show a slight improvement with respect to defect occurrences, however, these results are not statistically significant. The results showing an increase in development effort are significant. Based on the experiment we provide recommendations to improve the benefit obtained by using modeling conventions. The recommendations include improved adherence to the modeling conventions, training and experience, and developer motivation. Finally, we propose task-oriented views for UML. Task-oriented views are visualizations of UML models that support developers by providing the information that is necessary for a particular task, such as maintenance, comprehension, or quality analysis. We argue that the existing UML diagram types and existing UML tools do not provide the required information effectively. For example, it is tedious to find the relations between model elements in different diagrams and to relate data such as metrics, bug data, or evolution data to model elements. We discuss a framework that we used as a basis for creating task-oriented views. The proposed views are: MetaView, ContextView, MetricView, UML-City-View, Quality Tree View, and Evolution View. We conducted an experiment to validate the views with respect to comprehension tasks. The results are very promising and show that the correctness of comprehension is improved by 4.5% and that the effort for comprehension is reduced by 20%. The proposed task-oriented views are implemented in the tool MetricView Evolution

Interactive views to improve the comprehension of UML models - an experimental validation

Software development is becoming more and more model-centric. As a result models are used for a large variety of purposes, such as quality analysis, understanding, and maintenance. We argue that the UML and related existing tooling does not offer sufficient support to the developer to understand the models and evaluate their quality. We have proposed and implemented a collection of views to increase model understanding: MetaView, ContextView, MetricView, and UML-City-View. The purpose of this experiment is to validate whether there is a difference between the proposed views and the existing views with respect to comprehension correctness and comprehension effort. The comprehension task performed by the subjects was to answer a questionnaire about a model. 100 MSc students with relevant background knowledge have participated in the experiment. The results are statistically significant and show that the correctness is improved by 4.5% and that the time needed is reduced by 20%

Second International Workshop on Model Size Metrics

This paper reports on the Model Size Metrics (MSM) workshop held as satellite event of the MODELS 2007 conference. The focus of the workshop is to develop metrics for use in model-centric software development. As a starting point for discussion we focused on size. The workshop aim was to bring together researchers in this area, share experiences and discuss future directions. This paper summarizes the presentations that were given and the highlights of the discussion that followed and summarizes open issues for future work

MetricViewEvolution : UML-based views for monitoring model evolution and quality

As the role of models during software development and maintenance is becoming more and more important, techniques are needed to control a model's quality during evolution. We present our tool MetricViewEvolution as a step towards managing model quality during development and evolution. Six views are implemented in MetricViewEvolution that aid the user in tasks such as model understanding, identification of quality problems and evolution trends. The views combine structural model information with metrics data from inside the model and external sources. MetricViewEvolution has been applied successfully in industrial case studie

In practice : UML software architecture and design description

The Unified Modeling Language has attracted many organizations and practitioners. UML is now the de facto modeling language for software development. Several features account for its popularity: it's a standardized notation, rich in expressivity; UML 2.0 provides 13 diagram types that enable modeling several different views and abstraction levels. Furthermore, UML supports domain-specific extensions using stereotypes and tagged values. Finally, several case tools integrate UML modeling with other tasks such as generating code and reverse-engineering models from code. Our study focused on UML use and model quality in actual projects rather than on its adequacy as a notation or language

A visualization framework for task-oriented modelling using UML

The UML is a collection of 13 diagram notations to describe different views of a software system. The existing diagram types display model elements and their relations. Software engineering is becoming more and more model-centric, such that software engineers start using UML models for more tasks than just describing the system. Tasks such as analysis or prediction of system properties require additional information such as metrics of the UML model or from external sources, e.g. a version control system. In this paper we identify tasks of model-centric software engineering and information that is required to fulfil these tasks. We propose views to visualize the information to support fulfilling the tasks. This paper reports on industrial case studies and a light-weight user experiment to validate the usefulness of the proposed views that are implemented in our MetricView evolution too

An experimental investigation of UML modeling conventions

Modelers tend to exploit the various degrees of freedom provided by the UML. The lack of uniformity and the large amount of defects contained in UML models result in miscommunication between different readers. To prevent these problems we propose modeling conventions, analogue to coding conventions for programming. This work reports on a controlled experiment to explore the effect of modeling conventions on defect density and modeling effort. 106 masters’ students participated over a six-weeks period. Our results indicate that decreased defect density is attainable at the cost of increased effort when using modeling conventions, and moreover, that this trade-off is increased if tool-support is provided. Additionally we report observations on the subjects’ adherence to and attitude towards modeling conventions. Our observations indicate that efficient integration of convention support in the modeling process, e.g. through training and seamless tool integration, forms a promising direction towards preventing defects