Defining the process to literature searching in systematic reviews: a literature review of guidance and supporting studies

BACKGROUND: Systematic literature searching is recognised as a critical component of the systematic review process. It involves a systematic search for studies and aims for a transparent report of study identification, leaving readers clear about what was done to identify studies, and how the findings of the review are situated in the relevant evidence. Information specialists and review teams appear to work from a shared and tacit model of the literature search process. How this tacit model has developed and evolved is unclear, and it has not been explicitly examined before. The purpose of this review is to determine if a shared model of the literature searching process can be detected across systematic review guidance documents and, if so, how this process is reported in the guidance and supported by published studies. METHOD: A literature review. Two types of literature were reviewed: guidance and published studies. Nine guidance documents were identified, including: The Cochrane and Campbell Handbooks. Published studies were identified through 'pearl growing', citation chasing, a search of PubMed using the systematic review methods filter, and the authors' topic knowledge. The relevant sections within each guidance document were then read and re-read, with the aim of determining key methodological stages. Methodological stages were identified and defined. This data was reviewed to identify agreements and areas of unique guidance between guidance documents. Consensus across multiple guidance documents was used to inform selection of 'key stages' in the process of literature searching. RESULTS: Eight key stages were determined relating specifically to literature searching in systematic reviews. They were: who should literature search, aims and purpose of literature searching, preparation, the search strategy, searching databases, supplementary searching, managing references and reporting the search process. CONCLUSIONS: Eight key stages to the process of literature searching in systematic reviews were identified. These key stages are consistently reported in the nine guidance documents, suggesting consensus on the key stages of literature searching, and therefore the process of literature searching as a whole, in systematic reviews. Further research to determine the suitability of using the same process of literature searching for all types of systematic review is indicated

Renewable, ethical? Assessing the energy justice potential of renewable electricity

Energy justice is increasingly being used as a framework to conceptualize the impacts of energy decision making in more holistic ways and to consider the social implications in terms of existing ethical values. Similarly, renewable energy technologies are increasingly being promoted for their environmental and social benefits. However, little work has been done to systematically examine the extent to which, in what ways and in what contexts, renewable energy technologies can contribute to achieving energy justice. This paper assesses the potential of renewable electricity technologies to address energy justice in various global contexts via a systematic review of existing studies analyzed in terms of the principles and dimensions of energy justice. Based on publications including peer reviewed academic literature, books, and in some cases reports by government or international organizations, we assess renewable electricity technologies in both grid integrated and off-grid use contexts. We conduct our investigation through the rubric of the affirmative and prohibitive principles of energy justice and in terms of its temporal, geographic, socio-political, economic, and technological dimensions. Renewable electricity technology development has and continue to have different impacts in different social contexts, and by considering the different impacts explicitly across global contexts, including differences between rural and urban contexts, this paper contributes to identifying and understanding how, in what ways, and in what particular conditions and circumstances renewable electricity technologies may correspond with or work to promote energy justice

Connections between linear systems and convolutional codes

The article reviews different definitions for a convolutional code which can be found in the literature. The algebraic differences between the definitions are worked out in detail. It is shown that bi-infinite support systems are dual to finite-support systems under Pontryagin duality. In this duality the dual of a controllable system is observable and vice versa. Uncontrollability can occur only if there are bi-infinite support trajectories in the behavior, so finite and half-infinite-support systems must be controllable. Unobservability can occur only if there are finite support trajectories in the behavior, so bi-infinite and half-infinite-support systems must be observable. It is shown that the different definitions for convolutional codes are equivalent if one restricts attention to controllable and observable codes

Exploiting breakdown in nonhost effector-target interactions to boost host disease resistance

Plants are resistant to most microbial species due to non-host resistance (NHR), providing 36 broad-spectrum and durable immunity. However, the molecular components contributing to NHR are poorly characterised. Here, we address the question of whether failure of pathogen effectors to manipulate the non-host plant plays a critical role in NHR. RxLR effectors from two oomycete pathogens, Phytophthora infestans and Hyaloperonospora arabidopsidis, were able to enhance pathogen infection when expressed in host plants (Nicotiana benthamiana and Arabidopsis respectively) but the same effectors performed poorly in distantly-related non-host pathosystems. Putative target proteins in the host plant potato were identified for 64 P. infestans RxLR effectors using yeast-2-hybrid screens. Orthologues of these target proteins in the distantly related non-host plant Arabidopsis were identified and screened using matrix yeast-2-hybrid for interaction with RxLR effectors from both P. infestans and H. arabidopsidis. Few P. infestans effector- target protein interactions were conserved from potato to Arabidopsis target-orthologues (AtOrths). However, there was an enrichment of H. arabidopsidis RxLR effectors interacting with AtOrths. We expressed the AtOrth AtPUB33, which unlike its potato orthologue did not interact with P. infestans effector PiSFI3 in potato and Nicotiana benthamiana. The presence of AtPUB33 significantly reduced P. infestans colonisation in both host plants. Our results provide evidence that failure of pathogen effectors to interact with and/or correctly manipulate target proteins in distantly-related non-host plants contributes to NHR. Moreover, exploiting this breakdown in effector-nonhost target interaction, transferring effector target orthologues from non-host to host plants is a novel strategy to reduce disease