33 research outputs found
Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV
We report a measurement of the ratio of the bottom quark production cross
section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom
quarks with transverse momenta greater than 10.75 GeV identified through their
semileptonic decays and long lifetimes. The measured ratio
sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with
next-to-leading order (NLO) quantum chromodynamics (QCD)
Exploring Phenotypic and Genetic Overlap Between Cannabis Use and Schizotypy
There is a well-established relationship between cannabis use and psychosis, although the exact nature of this relationship is not fully understood. Recent studies have observed significant genetic overlap between a diagnosis of schizophrenia and lifetime cannabis use. Expanding on this work, the current study aimed to examine whether genetic overlap also occurs for subclinical psychosis (schizotypy) and cannabis use, as well as examining the phenotypic association between the traits. Phenotypic correlations were calculated for a variety of schizotypy and cannabis phenotypes in the UK Biobank (UKB), and single nucleotide polymorphism (SNP)-based heritability estimates and genetic correlations were calculated for these UKB phenotypes as well as for several other variables taken from recent genomewide association studies. Positive phenotypic correlations were observed between 11 out of 12 pairs of the cannabis use and schizotypy phenotypes (correlation range .05-.18), indicating a robust association between increased symptoms of schizotypy and cannabis use. SNP-based heritability estimates for two schizotypy phenotypes remained significant after multiple testing correction:social anhedonia(h(SNP)(2)= .08,SE= .02,N= 4025) andever seen an unreal vision(h(SNP)(2)= .35,SE= .10,N= 150,717). Finally, one significant genetic correlation was observed between schizotypy and cannabis use, a negative correlation betweensocial anhedoniaandnumber of times used cannabis(r(g)= -.30,p= .012). The current study suggests the relationship between cannabis use and psychosis is also seen in subclinical symptoms of psychosis, but further research with larger samples is needed to determine the biological mechanisms underlying this association.Peer reviewe
Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives
International audienceMultilayer III–V-based solar cells are complex devices consisting of many layers and interfaces. The study and the comprehension of the mechanisms that take place at the interfaces is crucial for efficiency improvement. In this work, we apply frequency-modulated Kelvin probe force microscopy under ambient conditions to investigate the capability of this technique for the analysis of an InP/GaInAs(P) multilayer stack. KPFM reveals a strong dependence on the local doping concentration, allowing for the detection of the surface potential of layers with a resolution as low as 20 nm. The analysis of the surface potential allowed for the identification of space charge regions and, thus, the presence of several junctions along the stack. Furthermore, a contrast enhancement in the surface potential image was observed when KPFM was performed under illumination, which is analysed in terms of the reduction of surface band bending induced by surface defects by photogenerated carrier distributions. The analysis of the KPFM data was assisted by means of theoretical modelling simulating the energy bands profile and KPFM measurements
Revealing of InP multi-layer stacks from KPFM measurements in the dark and under illumination
Solar cells are complex devices, being constituted of many layers and interfaces. The study and the comprehension of the mechanisms that take place at the interfaces is crucial for efficiency improvement. This paper applies Kelvin probe force microscopy (KPFM) to study materials and interfaces with nanometer scale imaging of the surface potential in the dark and under illumination. KPFM measurements are highly sensitive to surface states and to the experimental measurement environment influencing the atomic probe operating conditions. Therefore, in order to develop a quantitative understanding of KPFM measurements, we have prepared a dedicated structured sample with alternating layers of InP:S and InP:Fe whose doping densities were determined by secondary-ion mass spectroscopy. We have performed KPFM measurements and shown that we can spatially resolve 20 nm thick InP layers, notably when performed under illumination which is well-known to reduce the surface band-bending
Insect pollinators: linking research and policy. Workshop report.
EXECUTIVE SUMMARY
Pollinators interact with plants to underpin wider biodiversity, ecosystem function, ecosystem services to agricultural crops and ultimately human nutrition. The conservation of pollinators is thus an important goal.
Pollinators and pollination represent a tractable example of how biodiversity can be linked to an ecosystem service. This represents a case study for exploring the impacts of various policy instruments aiming to halt/reverse the loss of ecosystem services.
There is a need to understand how multiple pressures (e.g. habitat loss, fragmentation and degradation, climate change, pests and diseases, invasive species and environmental chemicals) can combine or interact to affect diversity, abundance and health of different pollinator groups.
Decision makers need to balance consideration of the effects of single pressures on pollinators against the suite of other pressures on pollinators. For instance, the threat from pesticide use (with its high public and media profile) also needs to be considered in the context of the other threats facing pollinators and balanced against the need for food security. An independent review of the balance of risks across pollinator groups from pesticide use would help synthesise current knowledge into an accessible form for decision makers.
To manage or lessen these threats to pollinators (wild and managed) and pollination requires improved knowledge about their basic ecology. We still need to know where and in what numbers different pollinator species occur, how they use different environments, how they interact with each other through shared plants and diseases and how wild pollinator abundance is changing.
Decision makers need clear factual evidence for i) the relative contribution of different managed and wild pollinator groups to wildflower and crop pollination and ii) how this varies across different land-uses, ecosystems and regions.
Addressing these basic and applied questions will improve our ability to forecast impacts on pollination service delivery to agricultural crops arising from current and future environmental changes, pesticide use and emerging diseases.
The development of a long-term, multi-scale monitoring scheme to monitor trends in pollinator (wild and managed) population size and delivery of pollination services (ideally tied to data collection on land-use, pesticide applications and disease incidence at relevant spatial scales) would provide the evidence base for developing the effectiveness of policy and management interventions over time.
Such a monitoring scheme would benefit from including research council organisations (e.g. CEH), governmental departments (e.g. Fera), universities, museums and NGOs (e.g. BBKA,SBA, Bumblebee Conservation Trust etc)
Insect Pollinators: linking research and policy Workshop Report | 5
In the context of agricultural intensification and conservation we need to establish what type, quality and quantity of interventions (e.g. agri-environment schemes, protected areas) are needed, where to place them and how they can sustain different pollinator populations and effective pollination services.
Current monitoring of the risks from diseases and pesticides requires broadening to consider other insects aside from honey bees, unless we can demonstrate that honey bees are good surrogates for all other pollinators.
There is a need to increase confidence in regulatory risk assessments pertaining to pathogens and pesticides by incorporating other pollinator species, investigating chronic exposure to multiple chemicals and using field relevant dosages (specific to regions, not using other data sources as surrogates).
At present the effects of spatial, social and temporal scales on the benefits stakeholders receive from pollination services are only beginning to be understood.
Economic valuation of pollination services can help optimise the cost-effectiveness of service management measures and offer new opportunities to incentivise action or raise awareness among stakeholders.
Novel tools and instruments (e.g. education and training) are needed to translate broad international (e.g. CBD, EU Biodiversity Strategy) and national (e.g. England‟s Biodiversity Strategy) policies into local actor (e.g. beekeeper, farmer, citizen scientist) contributions to meet biodiversity commitments
Refocusing some public funding to link basic science to development of practical solutions (e.g. better crop protection products, improved disease resistance or treatment) could help science deliver better-targeted evidence for pollinator protection.
Scientists need to make more use of opportunities (e.g. POSTnotes1; practitioner guides) to transfer knowledge to a broad audience in order to better influence decision maker and practitioner behaviours.
Improved knowledge exchange between scientists and decision makers is important to combating threats to pollination. Central to this is improved understanding of the respective positions of policy makers and scientists. For instance, policy-makers usually need to be presented with a range of options to balance against other areas of policy. Science does not always arrive at a consensus due to uncertainties in data or models. Policy-makers need to understand that scientists are communicating the “best available knowledge at present” and that consequently it is not always possible to give a definitive answer