44 research outputs found

    Self-Adaptation in Industry: A Survey

    Full text link
    Computing systems form the backbone of many areas in our society, from manufacturing to traffic control, healthcare, and financial systems. When software plays a vital role in the design, construction, and operation, these systems are referred as software-intensive systems. Self-adaptation equips a software-intensive system with a feedback loop that either automates tasks that otherwise need to be performed by human operators or deals with uncertain conditions. Such feedback loops have found their way to a variety of practical applications; typical examples are an elastic cloud to adapt computing resources and automated server management to respond quickly to business needs. To gain insight into the motivations for applying self-adaptation in practice, the problems solved using self-adaptation and how these problems are solved, and the difficulties and risks that industry faces in adopting self-adaptation, we performed a large-scale survey. We received 184 valid responses from practitioners spread over 21 countries. Based on the analysis of the survey data, we provide an empirically grounded overview of state-of-the-practice in the application of self-adaptation. From that, we derive insights for researchers to check their current research with industrial needs, and for practitioners to compare their current practice in applying self-adaptation. These insights also provide opportunities for the application of self-adaptation in practice and pave the way for future industry-research collaborations.Comment: 43 page

    Wolbachia colonization in drosophila midguts and its effects on intestinal stem cells

    Full text link
    Wolbachia is a vertically transmitted, obligate intracellular bacterium infecting ~40% of all known species of arthropods, as well as filarial nematodes. The nature of Wolbachia-host interactions ranges from reproductive parasitism to increased fecundity and pathogen protection. Wolbachia reduces the ability of mosquitoes to transmit human pathogens, which is being explored as a novel method for the control of vector-borne diseases like Dengue and Zika. The mechanisms of Wolbachia blocking the transmission of these diseases are not fully understood. There are studies indicating that Wolbachia-induced changes in the insect immunity could block the virus, however there is no consensus in the literature. A necessary step in the transmission of these diseases is the viral entry into the insect vector. This occurs trough the gut epithelium, highlighting the importance of understanding the interaction of this tissue with microorganisms. We have recently shown that Wolbachia colonizes the Drosophila gut epithelium and affects the gut microbiome composition. Wolbachia’s presence did not affect the gene expression of immune effector molecules from the main regulators of gut immunity, Imd and ROS pathways. Our understanding of the mechanisms of Wolbachia’s colonization of the gut epithelium and modulation of gut microbiome are still very limited. This work characterizes Wolbachia’s kinetics of colonization in Drosophila midguts. Imaging analysis revealed that Wolbachia colonizes adult and larval midguts in different patterns. We have also characterized a preferential colonization in specific adult midgut sub-regions. We observed that Wolbachia patches are confined to specific midgut subregions, in a pattern similar to the arrangement of intestinal stem cell (ISC) clones. These results led us to hypothesize that Wolbachia colonizes Drosophila midguts by infecting intestinal progenitor cells and spreading vertically to their progeny with limited lateral transmission between neighboring cells. We provide evidence to support this hypothesis by showing that Wolbachia is present in intestinal progenitor cells in all stages of the fly’s life cycle as well as by analyzing the infection status of ISC clones and differentiated cells surrounding ISCs. Finally, we found that ISC proliferation is reduced by the intracellular presence of Wolbachia, which also decreases ISC tumor incidence triggered by the downregulation of Notch signaling specifically in ISCs. These findings will aid in our understanding of Wolbachia tropisms and its phenotypic consequences. It has been shown that in the Wolbachia wMelPop strain excessive growth of intracellular bacteria leads to damage to the host cell, suggesting a mechanism of controlling intracellular growth in other strains. To better understand the molecular mechanisms behind Wolbachia-Drosophila interactions, we turned to the gonads, as Wolbachia colonization of these tissues has been well characterized. We chose to investigate the interplay between Reactive Oxygen Species (ROS) and Wolbachia, as intracellular ROS could regulate bacterial density but also be affected by Wolbachia and play a role in symbiont-related phenotypes. Using direct and indirect measurements of ROS, we show that the pathogenic strain wMelPop increases ROS in the germarium, while the symbiotic strains wMel and wMelCS reduce ROS in the terminal filaments. None of the Wolbachia strains tested affected ROS levels in the testes. In addition, genetically altering ROS levels in the germline or systemically in the fly did not affect Wolbachia levels in the ovaries. We conclude that ROS does not significantly affect Wolbachia in the fruit fly gonads

    Feature Papers in Horticulturae â…ˇ

    Get PDF
    Horticultural research has been undergoing fundamental changes to improve crop plants as a result of the emergence of new biochemical and molecular techniques. In addition, integration of new technologies with the desire to develop more sustainable production systems has also spurred production level research. The highlighted Feature Papers here reflect the diversity of the types of research performed on horticultural plant species, spanning basic to applied studies, production systems, and postharvest studies, in addition to highlighting some critical issues facing horticultural plant species

    Biodiversity of the Gulf of Guinea Oceanic Islands

    Get PDF
    This open access book presents a comprehensive synthesis of the biodiversity of the oceanic islands of the Gulf of Guinea, a biodiversity hotspot off the west coast of Central Africa. Written by experts, the book compiles data from a plethora of sources – archives, museums, bibliography, official reports and previously unpublished data – to provide readers with the most updated information about the biological richness of these islands and the conservation issues they face. The Gulf of Guinea Oceanic Islands (Príncipe, São Tomé and Annobón and surrounding islets) present extraordinary levels of endemism across different animal, fungi and plant groups. This very high endemism likely results from the long geological history of the islands and their proximity to the diversity-rich continent. Many researchers, students and conservationists from across the globe are interested in documenting biodiversity on the islands, understanding the evolutionary origins of this diversity, and mitigating the impacts of global change on this unique archipelago. This book aims to be a primer for a broad audience seeking baseline biodiversity information and to serve as a roadmap for future research efforts aiming to fill knowledge gaps in understanding and conserving the unparalleled biodiversity of the Gulf of Guinea islands

    The evolution and development of structural colour in Heliconius butterflies

    Get PDF
    In nature, nanostructures can interact with light to produce a striking array of colours called structural colours. Such colours have gained considerable attention in evolutionary biology and, more recently, as potential routes for the design of advanced optical materials. Vivid examples of structural colour are found in butterflies, resulting from the modification of their wing scales to contain optically precise nanostructures. In Heliconius, such optical nanostructures take the form of multilayer reflectors on the cuticle scale ridges which reflect light through constructive interference. While structural colours in Heliconius have been characterised optically, their underlying development remains unknown. Throughout this thesis, I explore the development of structural colour in Heliconius, both in terms of the cellular processes guiding the precise formation of the multilayer reflectors as well as the underlying genetic control. Using high-resolution microscopy and perturbation experiments, I demonstrate a crucial role of the actin cytoskeleton in the development of optical nanostructures in Heliconius sara. In addition, I reveal a previously undescribed network of actin in developing butterfly scale cells which forms at the time of optical nanostructure formation. I then use differential expression analysis between structurally coloured and non-structurally coloured subspecies of Heliconius erato and Heliconius melpomene to reveal a number of candidate genes that may control optical nanostructure formation. Furthermore, I reveal a lack of convergence in the genes controlling structural colour development in Heliconius. Finally, I demonstrate the development of structural colour in Heliconius is subject to environmental influences, specifically dietary stress. This thesis lays the foundation for investigations into the study of structural colour development in diverse butterfly species

    A model-based runtime environment for adapting communication systems

    Full text link
    With increasing network sizes, mobility, and traffic, it becomes a challenging task to achieve goals such as continuously delivering a satisfying service quality. Self-adaptive approaches use feedback loops to adapt a managed resource at runtime according to changes in the execution context. Adding self-adaptive capabilities to communication systems-computer networks as well as supporting structures such as overlays or middleware-is a major research focus. However, making a communication system self-adaptive is a challenging task for communication system developers. First, the distributed nature of such systems requires the collection of monitoring information from multiple hosts and the adaptation of distributed components. Second, communication systems consist of heterogeneous components, which are, e.g., developed in different programming languages. Third, system developers typically lack knowledge about the development of self-adaptive systems. Hence, this work's overall goal is to allow system developers to focus on making a (legacy) communication system adaptive. Motivated by these observations, this thesis proposes a model-based runtime environment for adapting communication systems called REACT. In contrast to self-adaptation frameworks, which offer a standard way to build self-adaptive applications, we refer to REACT as a runtime environment, i.e., a platform that is additionally able to plan and execute adaptations based on user-specified adaptation behavior. REACT includes the support for decentralized adaptation logics and distributed systems, multiple programming languages, as well as tool support and assistance for developers. The developer support is achieved using model-based techniques for specifying the reconfiguration behavior of the adaptation logic. Also, this thesis proposes an easy-to-follow development process. As part of that, it is needed to monitor the reconfiguration behavior of the self-adaptive system. Hence, this work also presents two dashboard-based visualization approaches called CoalaViz and EnTrace for providing traceability of self-adaptive systems for system developers and administrators. This thesis follows a design science research methodology resulting in the design and implementation of the final artifacts. By that, this dissertation presents different REACT Loops, including specific ways to model and plan the adaptive behavior using satisfiability, mixed-integer linear programming, and constraint solvers. The prototypes of these approaches, including the two visualization solutions, are evaluated in multiple use cases. Therefore, this work provides an end-to-end solution for specifying the adaptive behavior, connecting a managed resource, deploying the system, as well as debugging and monitoring it

    Manage Weeds on Your Farm: A Guide to Ecological Strategies

    Get PDF
    Manage Weeds on Your Farm is a definitive guide to understanding agricultural weeds and how to manage them efficiently, effectively and ecologically—for organic and conventional farmers alike. With the growing spread of herbicide-resistant weeds and with the public’s embrace of sustainably raised foods, farmers everywhere, both organic and conventional, are seeking better ways to eliminate or reduce their use of synthetic herbicides. The ecological approach to weed management seeks to first understand the biology and behavior of problem weeds and then to develop an integrated set of control strategies that exploit their weaknesses. Manage Weeds on Your Farm: A Guide to Ecological Strategies provides you with in-depth information about dozens of agricultural weeds found throughout the country and the best ways of managing them. In Part One, the book begins with a general discussion of weeds: their biology, behavior and the characteristics that influence how to best control their populations. It then describes the strengths and limitations of the most common cultural management practices, physical practices and cultivation tools. Part Two is a reference section that describes the identification, ecology and management of 63 of the most common and difficult-to-control weed species found in the United States. Ecological weed management is knowledge intensive, rather than input intensive. But it doesn’t have to be excessively labor intensive. Manage Weeds on Your Farm shows you how to outsmart your weeds by identifying the right tactic for the right weed at the right time, which will reduce as much as possible the labor required, while ensuring your weeds don’t impact crop yields. Note: Manage Weeds on Your Farm is focused on the weeds of arable cropping systems. It does not discuss the management of weeds in forests, turf, permanent pastures or perennial bioenergy crops. Weed management issues in forage production are discussed to some extent since forages are often rotated with other crops

    Polarized light - host location and selection cue in phytophagous insects?

    Get PDF
    Insect herbivores exploit plant cues to discern host and non-host plants. Studies of visual plant cues have focused on color despite the inherent polarization sensitivity of insect photoreceptors and the information carried by polarization of foliar reflectance, most notably the degree of linear polarization (DoLP; 0-100%). The DoLP of foliar reflection was hypothesized to be a host plant cue for insects but was never experimentally tested. I investigated the use of these polarization cues by the cabbage white butterfly, Pieris rapae (Pieridae). This butterfly has a complex visual system with several different polarization-sensitive photoreceptors, as characterized with electrophysiology and histology. I applied photo polarimetry revealing large differences in the DoLP of leaf-reflected light among plant species generally and between host and non-host plants of P. rapae specifically. As polarized light cues are directionally dependent, I also tested, and modelled, the effect of approach trajectory on the polarization of plant-reflected light and the resulting attractiveness to P. rapae, showing that certain approach trajectories are optimal for discriminating among plants based on these cues. I then demonstrated that P. rapae exploit the DoLP of foliar reflections to discriminate among plants. In experiments with paired digital plant images that allowed for independent control of polarization, color and intensity, P. rapae females preferred images of the host plant cabbage with a low DoLP (31%) to images of the non-host plant potato with a high DoLP (50%). These results indicated that the DoLP had a greater effect on foraging decisions than the differential color, intensity or shape of the two plant images. To investigate potential neurological mechanisms, I designed behavioral bioassays presenting choices between images that differed in color, intensity and/or DoLP. The combined results of these bioassays suggest that several photoreceptor classes are involved and that P. rapae females process and interpret polarization reflections in a way different from that described for other polarization-sensitive taxa. My work has focused on P. rapae and its host plants but there is every reason to believe that the DoLP of foliar reflection is an essential plant cue that may commonly be exploited by foraging insect herbivore

    REACT-ION: A model-based runtime environment for situation-aware adaptations

    Full text link
    Trends such as the Internet of Things lead to a growing number of networked devices and to a variety of communication systems. Adding self-adaptive capabilities to these communication systems is one approach to reducing administrative effort and coping with changing execution contexts. Existing frameworks can help reducing development effort but are neither tailored toward the use in communication systems nor easily usable without knowledge in self-adaptive systems development. Accordingly, in previous work, we proposed REACT, a reusable, model-based runtime environment to complement communication systems with adaptive behavior. REACT addresses heterogeneity and distribution aspects of such systems and reduces development effort. In this article, we propose REACT-ION—an extension of REACT for situation awareness. REACT-ION offers a context management module that is able to acquire, store, disseminate, and reason on context data. The context management module is the basis for (i) proactive adaptation with REACT-ION and (ii) self-improvement of the underlying feedback loop. REACT-ION can be used to optimize adaptation decisions at runtime based on the current situation. Therefore, it can cope with uncertainty and situations that were not foreseeable at design time. We show and evaluate in two case studies how REACT-ION’s situation awareness enables proactive adaptation and self-improvement
    corecore