47 research outputs found
A methodology for systematic mapping in environmental sciences
Systematic mapping was developed in social sciences in response to a lack of empirical data when answering questions using systematic review methods, and a need for a method to describe the literature across a broad subject of interest. Systematic mapping does not attempt to answer a specific question as do systematic reviews, but instead collates, describes and catalogues available evidence (e.g. primary, secondary, theoretical, economic) relating to a topic or question of interest. The included studies can be used to identify evidence for policy-relevant questions, knowledge gaps (to help direct future primary research) and knowledge clusters (sub-sets of evidence that may be suitable for secondary research, for example systematic review). Evidence synthesis in environmental sciences faces similar challenges to those found in social sciences. Here we describe the translation of systematic mapping methodology from social sciences for use in environmental sciences. We provide the first process-based methodology for systematic maps, describing the stages involved: establishing the review team and engaging stakeholders; setting the scope and question; setting inclusion criteria for studies; scoping stage; protocol development and publication; searching for evidence; screening evidence; coding; production of a systematic map database; critical appraisal (optional); describing and visualising the findings; report production and supporting information. We discuss the similarities and differences in methodology between systematic review and systematic mapping and provide guidance for those choosing which type of synthesis is most suitable for their requirements. Furthermore, we discuss the merits and uses of systematic mapping and make recommendations for improving this evolving methodology in environmental sciences
Evidence for the effects of neonicotinoids used in arable crop production on non-target organisms and concentrations of residues in relevant matrices: a systematic map protocol
Background
Neonicotinoid insecticides (NNIs) have been routinely used in arable crop protection since their development in the early 1990s. These insecticides have been subject to the same registration procedures as other groups of pesticides, thus meet the same environmental hazard standards as all crop protection products. However, during the last 10 years the debate regarding their possible detrimental impact on non-target organisms, particularly pollinators, has become increasingly contentious and widely debated. Against this background, legislators and politicians in some countries, have been faced with a need to make decisions on the future registration of some or all of this class of insecticides, based on published evidence that in some areas is incomplete or limited in extent. This has created much concern in agricultural communities that consider that the withdrawal of these insecticides is likely to have significant negative economic, socio-economic and environmental consequences.
Methods
The proposed systematic map aims to address the following primary question: What is the available evidence for the effects of neonicotinoids used in arable crop production on non-target organisms and concentrations of residues in relevant matrices? The primary question will be divided into two sub-questions to gather research literature for (1) the effect of NNIs on non-target organisms (2) the occurrence of concentrations of NNIs in matrices of relevance to non-target organisms (i.e. exposure routes). The systematic map will focus on NNIs used in arable crop production: imidacloprid, clothianidin, thiamethoxam, acetamiprid, thiacloprid and dinotefuran. Separate inclusion criteria have been developed for each sub-question. Traditional academic and grey literature will be searched for in English language and a searchable databases containing extracted meta-data from relevant included studies will be developed
Comparison of three soil health indicators between different vegetative strip compositions
Contemporary evidence shows biotic factors play a prominent role in the soil health and the provision of soil functions. Herbaceous grassland species differ in their modulation of soil communities, effects on soil components, as well the processes they interact with or regulate. In this study, we aimed to investigate the impact of different plant species communities on soil health, as quantified by soil physical (water infiltration), chemical (soil organic matter) and biological (Collembola community data) indicators. Data was collected from an existing long-term field trial in the UK, planted to either forb-dominated composition, grass species dominated composition or a multipurpose mixture of forb and grass species. Results showed that plant community can determine soil water infiltration rates, particularly with observed increased soil organic matter (SOM) and epigeic Collembola abundances. The results presented here add evidence that plant communities planted as vegetative buffer strips can be specifically tailored to support soil health development and maintenance
The application of allelopathy in integrated pest management systems to control temperate European crop pests: a systematic map
Background
Pesticides perform vital roles within agriculture but growing concern for their impact on the environment and non-target organisms has created a market for biopesticides with fewer ecological impacts. One source of biopesticides is allelochemicals, here defined as compounds released by an organism that have an inhibitory or stimulatory effect on neighbouring organisms. The focus of this study is allelopathic plants and their inhibitory effects on invertebrate herbivorous agricultural pests of temperate Europe. A systematic map is required to describe the current state of research and collate evidence.
Methods
Two academic databases were searched for relevant studies in temperate climates. The results were imported into EPPI-Reviewer, duplicates removed, studies screened and data extracted into a searchable database following the inclusion criteria and coding tool set out in the protocol. Screening consistency was checked at each stage using 5% of the studies. Critical appraisal was not conducted. Each unique combination of key variables (pest, plant, allelochemical, application method, intervention form) was treated as a separate datapoint or experiment. The data was then analysed and cross-tabulated to produce descriptive statistics and heatmaps.
Results
This systematic map produced a database which included 243 studies containing 717 experiments from 5550 initial results. Research was unevenly distributed among all key variables with a distinct bias towards extracted allelochemical experiments under laboratory conditions. Allyl isothiocyanate was the most studied allelochemical and of the 99 identified chemical groups, flavonoids and glucosinolates were the most frequent. A wide range of pest and plant species were identified. Brassicas were the most studied plant family and Lepidoptera the most studied pest order. Physical living plants, as opposed to plant extracts or isolated allelochemicals, were predominantly studied in terms of resistance. Allelopathy application methods were not specified in the abstract of 22% of experiments and only 10% of experiments were conducted under field conditions.
Conclusion
Allelopathy has been studied in the context of temperate invertebrate pest control in some breadth but little depth and key pest species have not been targeted. The map highlighted significant gaps in the evidence base and a distinct lack of field studies or studies comparing application methods. It contains insufficient evidence to guide policy or management decisions, but provides a research tool and indicates areas for future studies including highlighting topics for secondary research. Critical appraisal is needed to determine allelopathic affect and future search strings should detail all application methods
Diffuse Neutron Scattering Study of a Disordered Complex Perovskite Pb(Zn1/3Nb2/3)O3 Crystal
Diffuse scattering around the (110) reciprocal lattice point has been
investigated by elastic neutron scattering in the paraelectric and the relaxor
phases of the disordered complex perovskite crystal-Pb(Zn1/3Nb2/3)O3(PZN). The
appearance of a diffuse intensity peak indicates the formation of polar
nanoregions at temperature T*, approximately 40K above Tc=413K. The analysis of
this diffuse scattering indicates that these regions are in the shape of
ellipsoids, more extended in the direction than in the direction.
The quantitative analysis provides an estimate of the correlation length, \xi,
or size of the regions and shows that \xi ~1.2\xi , consistent with
the primary or dominant displacement of Pb leading to the low temperature
rhombohedral phase. Both the appearance of the polar regions at T*and the
structural transition at Tc are marked by kinks in the \xi curve but not
in the \xi one, also indicating that the primary changes take place in a
direction at both temperatures.Comment: REVTeX file. 4 pages, 3 figures embedded, New version after referee
cond-mat/010605
A solution of the coincidence problem based on the recent galactic core black hole mass density increase
A mechanism capable to provide a natural solution to two major cosmological
problems, i.e. the cosmic acceleration and the coincidence problem, is
proposed. A specific brane-bulk energy exchange mechanism produces a total dark
pressure, arising when adding all normal to the brane negative pressures in the
interior of galactic core black holes. This astrophysically produced negative
dark pressure explains cosmic acceleration and why the dark energy today is of
the same order to the matter density for a wide range of the involved
parameters. An exciting result of the analysis is that the recent rise of the
galactic core black hole mass density causes the recent passage from cosmic
deceleration to acceleration. Finally, it is worth mentioning that this work
corrects a wide spread fallacy among brane cosmologists, i.e. that escaping
gravitons result to positive dark pressure.Comment: 14 pages, 3 figure
Integrated motor drives: state of the art and future trends
With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system.
This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented
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Energetic particle influence on the Earth's atmosphere
This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally
galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere
are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earthâs atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere
Search for TeV-scale gravity signatures in high-mass final states with leptons and jets with the ATLAS detector at sqrt [ s ] = 13TeV
A search for physics beyond the Standard Model, in final states with at least one high transverse momentum charged lepton (electron or muon) and two additional high transverse momentum leptons or jets, is performed using 3.2 fbâ1 of protonâproton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015 at âs = 13 TeV. The upper end of the distribution of the scalar sum of the transverse momenta of leptons and jets is sensitive to the production of high-mass objects. No excess of events beyond Standard Model predictions is observed. Exclusion limits are set for models of microscopic black holes with two to six extra dimensions
Search for high-mass new phenomena in the dilepton final state using protonâproton collisions at View the MathML sources=13TeV with the ATLAS detector
A search is conducted for both resonant and non-resonant high-mass new phenomena in dielectron and dimuon final states. The search uses View the MathML source3.2fbâ1 of protonâproton collision data, collected at View the MathML sources=13TeV by the ATLAS experiment at the LHC in 2015. The dilepton invariant mass is used as the discriminating variable. No significant deviation from the Standard Model prediction is observed; therefore limits are set on the signal model parameters of interest at 95% credibility level. Upper limits are set on the cross-section times branching ratio for resonances decaying to dileptons, and the limits are converted into lower limits on the resonance mass, ranging between 2.74 TeV and 3.36 TeV, depending on the model. Lower limits on the ââqqââqq contact interaction scale are set between 16.7 TeV and 25.2 TeV, also depending on the mode