922 research outputs found
Pareto-efficient biological pest control enable high efficacy at small costs
Biological pest control is increasingly used in agriculture as a an alternative to traditional chemical pest control. In many cases, this involves a one-off or periodic release of entomopathogens. As the interaction between the entomopathogen and the pest is complex and the production of entomopathogens potentially expensive, it is not surprising that both the efficacy and economic viability of biological pest control are debated. Here, we investigate the performance of very simple control strategies. In particular, we show how Pareto-efficient one-off or periodic release strategies, which optimally trade off between efficacy and economic viability, can be devised and used to enable high efficacy for small economic costs. We demonstrate our method on a pest-pathogen-crop model with a tunable immigration rate of pests. By analyzing this model, we demonstrate that simple Pareto-efficient one-off release strategies are typically efficacious and simultaneously have average profits that are close to the theoretical maximum obtained by less efficacious and complicated profit-optimizing strategies. The only exception occurs for high pest-immigration rates, in which case periodic release is preferable. The methods presented here can be extended to more complex scenarios and thus be used to identify promising biological pest control strategies in many circumstances
Adult attachment style across individuals and role-relationships: Avoidance is relationship-specific, but anxiety shows greater generalizability
A generalisability study examined the hypotheses that avoidant attachment, reflecting the representation of others, should be more relationship-specific (vary across relationships more than across individuals), while attachment anxiety, reflecting self-representation, should be more generalisable across a person’s relationships. College students responded to 6-item questionnaire measures of these variables for 5 relationships (mother, father, best same-gender friend, romantic partner or best opposite-gender friend, other close person), on 3 (N = 120) or 2 (N = 77) occasions separated by a few weeks. Results supported the hypotheses, with the person variance component being larger than the relationship-specific component for anxiety, and the opposite happening for avoidance. Anxiety therefore seems not to be as relationship-specific as previous research suggested. Possible reasons for discrepancies between the current and previous studies are discussed
DNA hybridization to mismatched templates: a chip study
High-density oligonucleotide arrays are among the most rapidly expanding
technologies in biology today. In the {\sl GeneChip} system, the reconstruction
of the target concentration depends upon the differential signal generated from
hybridizing the target RNA to two nearly identical templates: a perfect match
(PM) and a single mismatch (MM) probe. It has been observed that a large
fraction of MM probes repeatably bind targets better than the PMs, against the
usual expectation from sequence-specific hybridization; this is difficult to
interpret in terms of the underlying physics. We examine this problem via a
statistical analysis of a large set of microarray experiments. We classify the
probes according to their signal to noise () ratio, defined as the
eccentricity of a (PM, MM) pair's `trajectory' across many experiments. Of
those probes having large () only a fraction behave consistently with
the commonly assumed hybridization model. Our results imply that the physics of
DNA hybridization in microarrays is more complex than expected, and they
suggest new ways of constructing estimators for the target RNA concentration.Comment: 3 figures 1 tabl
Chapter 10 - Detection and attribution of climate change: From global to regional
This chapter assesses the causes of observed changes assessed in Chapters 2 to 5 and uses understanding of physical processes, climate models and statistical approaches. The chapter adopts the terminology for detection and attribution proposed by the IPCC good practice guidance paper on detection and attribution (Hegerl et al., 2010) and for uncertainty Mastrandrea et al. (2011). Detection and attribution of impacts of climate changes are assessed by Working Group II, where Chapter 18 assesses the extent to which atmospheric and oceanic changes influence ecosystems, infrastructure, human health and activities in economic sectors
Nonresonant Three-body Decays of D and B Mesons
Nonresonant three-body decays of D and B mesons are studied. It is pointed
out that if heavy meson chiral perturbation theory (HMChPT) is applied to the
heavy-light strong and weak vertices and assumed to be valid over the whole
kinematic region, then the predicted decay rates for nonresonant charmless
3-body B decays will be too large and especially B^- --> pi^- K^+ K^- greatly
exceeds the current experimental limit. This can be understood as chiral
symmetry has been applied there twice beyond its region of validity. If HMChPT
is applied only to the strong vertex and the weak transition is accounted for
by the form factors, the dominant B^* pole contribution to the tree-dominated
direct three-body B decays will become small and the branching ratio will be of
order 10^{-6}. The decay modes B^- --> (K^- h^+ h^-)_{NR} and bar{B}^0 -->
(bar{K}^0 h^+h^-)_{NR} for h = pi, K are penguin dominated. We apply HMChPT in
two different cases to study the direct 3-body D decays and compare the results
with experiment. Theoretical uncertainties are discussed.Comment: 24 pages, 2 figures. New experimental results of direct 3-body D
decays as Reported at ICHEP2002 are included. To appear in Phys. Re
Magnetic reversal processes and critical thickness in FePt/{\alpha}-Fe/FePt trilayers
Magnetic reversal processes of a FePt/{\alpha}-Fe/FePt trilayer system with
in-plane easy axes have been investigated within a micromagnetic approach. It
is found that the magnetic reversal process consists of three steps: nucleation
of a prototype of domain wall in the soft phase, the evolution as well as the
motion of the domain wall from the soft to the hard phase and finally, the
magnetic reversal of the hard phase. For small soft layer thickness Ls, the
three steps are reduced to one single step, where the magnetizations in the two
phases reverse simultaneously and the hysteresis loops are square with
nucleation as the coercivity mechanism. As Ls increases, both nucleation and
pinning fields decrease. In the meantime, the single-step reversal expands to a
standard three-step one and the coercivity mechanism changes from nucleation to
pinning. The critical thickness where the coercivity mechanism alters, could be
derived analytically, which is found to be inversely proportional to the square
root of the crystalline anisotropy of the hard phase. Further increase of Ls
leads to the change of the coercivity mechanism from pinning to nucleation.Comment: 21 pages, 5 figures, pdf file, figures include
Coastal squeeze on temperate reefs: Long-term shifts in salinity, water quality, and oyster-associated communities
Foundation species, such as mangroves, saltmarshes, kelps, seagrasses, and oysters, thrive within suitable environmental envelopes as narrow ribbons along the land–sea margin. Therefore, these habitat-forming species and resident fauna are sensitive to modified environmental gradients. For oysters, many estuaries impacted by sea-level rise, channelization, and municipal infrastructure are experiencing saltwater intrusion and water-quality degradation that may alter reef distributions, functions, and services. To explore decadal-scale oyster–reef community patterns across a temperate estuary in response to environmental change, we resampled reefs in the Newport River Estuary (NRE) during 2013–2015 that had previously been studied during 1955–1956. We also coalesced historical NRE reef distribution (1880s–2015), salinity (1913–2015), and water-quality-driven shellfish closure boundary (1970s–2015) data to document environmental trends that could influence reef ecology and service delivery. Over the last 60–120 years, the entire NRE has shifted toward higher salinities. Consequently, oyster–reef communities have become less distinct across the estuary, manifest by 20%–27% lower species turnover and decreased faunal richness among NRE reefs in the 2010s relative to the 1950s. During the 2010s, NRE oyster–reef communities tended to cluster around a euhaline, intertidal-reef type more so than during the 1950s. This followed faunal expansions farther up estuary and biological degradation of subtidal reefs as NRE conditions became more marine and favorable for aggressive, reef-destroying taxa. In addition to these biological shifts, the area of suitable bottom on which subtidal reefs persist (contracting due to up-estuary intrusion of marine waters) and support human harvest (driven by water quality, eroding from up-estuary) has decreased by >75% since the natural history of NRE reefs was first explored. This “coastal squeeze” on harvestable subtidal oysters (reduced from a 4.5-km to a 0.75-km envelope along the NRE's main axis) will likely have consequences regarding the economic incentives for future oyster conservation, as well as the suite of services delivered by remaining shellfish reefs (e.g., biodiversity maintenance, seafood supply). More broadly, these findings exemplify how “squeeze” may be a pervasive concern for biogenic habitats along terrestrial or marine ecotones during an era of intense global change
Residual Partial Least Squares Learning: Brain Cortical Thickness Simultaneously Predicts Eight Non-pairwise-correlated Behavioural and Disease Outcomes in Alzheimer's Disease.
Alzheimer's Disease (AD) is the leading cause of dementia. It results in cortical thickness changes and is associated with a decline in cognition and behaviour. Such decline affects multiple important day-to-day functions, including memory, language, orientation, judgment and problem-solving. Recent research has made important progress in identifying brain regions associated with single outcomes, such as individual AD status and general cognitive decline. The complex projection from multiple brain areas to multiple AD outcomes, however, remains poorly understood. This makes the assessment and especially the prediction of multiple AD outcomes - each of which may unveil an integral yet different aspect of the disease - challenging, particularly when some are not strongly correlated. Here, uniting residual learning, partial least squares (PLS), and predictive modelling, we develop an explainable, generalisable, and reproducible method called the Residual Partial Least Squares Learning (the re-PLS Learning) to (1) chart the pathways between large-scale multivariate brain cortical thickness data (inputs) and multivariate disease and behaviour data (outcomes); (2) simultaneously predict multiple, non-pairwise-correlated outcomes; (3) control for confounding variables (e.g., age and gender) affecting both inputs and outcomes and the pathways in-between; (4) perform longitudinal AD disease status classification and disease severity prediction. We evaluate the performance of the proposed method against a variety of alternatives on data from AD patients, subjects with mild cognitive impairment (MCI), and cognitively normal individuals from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Our results unveil pockets of brain areas in the temporal, frontal, sensorimotor, and cingulate areas whose cortical thickness may be respectively associated with declines in different cognitive and behavioural subdomains in AD. Finally, we characterise re-PLS' geometric interpretation and mathematical support for delivering meaningful neurobiological insights and provide an open software package (re-PLS) available at https://github.com/thanhvd18/rePLS
Database of novel magnetic materials for high-performance permanent magnet development
This paper describes the open Novamag database that has been developed for the design of novel Rare-Earth free/lean permanent magnets. Its main features as software technologies, friendly graphical user interface, advanced search mode, plotting tool and available data are explained in detail. Following the philosophy and standards of Materials Genome Initiative, it contains significant results of novel magnetic phases with high magnetocrystalline anisotropy obtained by three computational high-throughput screening approaches based on a crystal structure prediction method using an Adaptive Genetic Algorithm, tetragonally distortion of cubic phases and tuning known phases by doping. Additionally, it also includes theoretical and experimental data about fundamental magnetic material properties such as magnetic moments, magnetocrystalline anisotropy energy, exchange parameters, Curie temperature, domain wall width, exchange stiffness, coercivity and maximum energy product, that can be used in the study and design of new promising high-performance Rare-Earth free/lean permanent magnets. The results therein contained might provide some insights into the ongoing debate about the theoretical performance limits beyond Rare-Earth based magnets. Finally, some general strategies are discussed to design possible experimental routes for exploring most promising theoretical novel materials found in the database.European Horizon 2020 Framework Programme for Research and Innovation (2014-2020) under Grant Agreement No. 686056, NOVAMAG. European Regional Development Fund in the IT4Innovations national supercomputing center – path to exascale project, project number CZ 02.1.01/0.0/0.0/16–013/0001791 within the Operational Programme Research, Development and Educatio
Influence Diagrams With Memory States: Representation and Algorithms
Abstract. Influence diagrams (IDs) offer a powerful framework for decision making under uncertainty, but their applicability has been hindered by the exponential growth of runtime and memory usage—largely due to the no-forgetting assumption. We present a novel way to maintain a limited amount of memory to inform each decision and still obtain near-optimal policies. The approach is based on augmenting the graphical model with memory states that represent key aspects of previous observations—a method that has proved useful in POMDP solvers. We also derive an efficient EM-based message-passing algorithm to compute the policy. Experimental results show that this approach produces highquality approximate polices and offers better scalability than existing methods.
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