3,346 research outputs found

    Relationship Between Fruit Yield and Damage by Codling Moth and Plum Curculio in a Biologically-Managed Apple Orchard

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    Fruit yield, codling moth (Cydia pomonella) damage, and plum curculio (Conotrachelus nenuphar) damage were monitored over an 8-year period in a O.5-ha, biologically-managed apple orchard in southwestern Michigan. The relationship between yield and damage was examined for both of these pests. The orchard showed clear biennial bearing patterns of alternating high and low yields. A significant negative correlation was found for yield and percent- age damage by codling moth but not for plum curculio damage. However, the estimated amount of fruit damaged by codling moth remained relatively stable over the period, indicating that changes in percentage damage depended on yield dynamics rather than changes in codling moth abundance. In contrast, the amount of fruit damaged by plum curculio showed biennial fluctuations and a positive correlation with yield, indicating that the population of this pest was capable of responding with increased oviposition in years with greater fruit yield. In addition, a comparison of codling moth fruit injury in years with and without the use of pheromone mating disruption showed no statistically significant reduction in damage as a result of using this method, suggesting that the orchard may be too small or codling moth populations too high for effective use of this management tactic

    Relationship Between Fruit Yield and Damage by Codling Moth and Plum Curculio in a Biologically-Managed Apple Orchard

    Get PDF
    Fruit yield, codling moth (Cydia pomonella) damage, and plum curculio (Conotrachelus nenuphar) damage were monitored over an 8-year period in a O.5-ha, biologically-managed apple orchard in southwestern Michigan. The relationship between yield and damage was examined for both of these pests. The orchard showed clear biennial bearing patterns of alternating high and low yields. A significant negative correlation was found for yield and percent- age damage by codling moth but not for plum curculio damage. However, the estimated amount of fruit damaged by codling moth remained relatively stable over the period, indicating that changes in percentage damage depended on yield dynamics rather than changes in codling moth abundance. In contrast, the amount of fruit damaged by plum curculio showed biennial fluctuations and a positive correlation with yield, indicating that the population of this pest was capable of responding with increased oviposition in years with greater fruit yield. In addition, a comparison of codling moth fruit injury in years with and without the use of pheromone mating disruption showed no statistically significant reduction in damage as a result of using this method, suggesting that the orchard may be too small or codling moth populations too high for effective use of this management tactic

    Jumble Java Byte Code to Measure the Effectiveness of Unit Tests

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    Jumble is a byte code level mutation testing tool for Java which inter-operates with JUnit. It has been designed to operate in an industrial setting with large projects. Heuristics have been included to speed the checking of mutations, for example, noting which test fails for each mutation and running this first in subsequent mutation checks. Significant effort has been put into ensuring that it can test code which uses custom class loading and reflection. This requires careful attention to class path handling and coexistence with foreign class-loaders. Jumble is currently used on a continuous basis within an agile programming environment with approximately 370,000 lines of Java code under source control. This checks out project code every fifteen minutes and runs an incremental set of unit tests and mutation tests for modified classes. Jumble is being made available as open source

    Modelling heterogeneity in scale directly: implications for estimates of influence in freight decision-making groups

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    The state of practice in the modelling of heterogeneous preferences does not separate the effects of scale from estimated mean and standard deviation preference measures. This restriction could lead to divergent behavioural implications relative to a flexible modelling structure that accounts for scale effects independently of estimated distributions of preference measures. The generalised multinomial logit (GMNL) model is such an econometric tool, enabling the analyst to identify the role that scale plays in impacting estimated sample mean and standard deviation preference measures, including confirming whether the appropriate model form approaches standard cases such as mixed logit. The GMNL model is applied in this paper to compare the behavioural implications of the minimum information group inference (MIGI) model within a study of interdependent road freight stakeholders in Sydney, Australia. MIGI estimates within GMNL models are compared with extant mixed logit measures (see Hensher and Puckett, 2008) to confirm whether the implications of the restrictive (with respect to scale) mixed logit model are consistent to those from the more flexible GMNL model. The results confirm the overall implication that transporters appear to hold relative power over supply chain responses to variable road-user charges. However, the GMNL model identifies a broader range of potential group decision-making outcomes and a restricted set of attributes over which heterogeneity in group influence is found than the mixed logit model. Hence, this analysis offers evidence that failing to account for scale heterogeneity may result in inaccurate representations of the bargaining set, and the nature of preference heterogeneity, in general

    The Nitrate Time Bomb (NTB) Model: a simple but effective method to investigate the impacts of historical nitrate loading on long-term groundwater nitrate concentrations

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    Nitrate water pollution, which remains an international problem, can cause long-term environmental damage and threaten both the economy and human health. Agricultural land is the major source of nitrate water pollution. It can take decades for nitrate leached from the soil to discharge into freshwaters. However, this nitrate time lag in the groundwater system has generally been ignored within the water resource management in many countries including the UK. We present a nitrate time bomb (NTB) model to modelling nitrate processes in the groundwater system. Whilst NTB contains simplified conceptual models, it can represent the major nitrate and hydrogeological processes in the groundwater system at both national and catchment scales, such as spatio-temporal nitrate loading, low-permeability superficial deposits, dual-porosity unsaturated zones and nitrate dilution in aquifers. The NTB model has been successfully used to simulate annual nitrate concentrations from 1925 to 2150 in the major aquifers in Great Britain and four local aquifer zones in the Eden Catchment, England. Monte Carlo simulations were undertaken to analyse parameter sensitivity and calibrate the model using observed datasets. These results help decision makers to understand how the historical nitrate loading from agricultural land affects the evolution of groundwater quality due to the nitrate time lag in the groundwater system. This NTB approach will be particularly valuable to evaluate the long-term impact and timescale of land management scenarios and programmes of measures introduced to help deliver water quality compliance. This model requires relatively modest parameterisation and is readily transferable to other areas

    Lifespan Regulation by Evolutionarily Conserved Genes Essential for Viability

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    Evolutionarily conserved mechanisms that control aging are predicted to have prereproductive functions in order to be subject to natural selection. Genes that are essential for growth and development are highly conserved in evolution, but their role in longevity has not previously been assessed. We screened 2,700 genes essential for Caenorhabditis elegans development and identified 64 genes that extend lifespan when inactivated postdevelopmentally. These candidate lifespan regulators are highly conserved from yeast to humans. Classification of the candidate lifespan regulators into functional groups identified the expected insulin and metabolic pathways but also revealed enrichment for translation, RNA, and chromatin factors. Many of these essential gene inactivations extend lifespan as much as the strongest known regulators of aging. Early gene inactivations of these essential genes caused growth arrest at larval stages, and some of these arrested animals live much longer than wild-type adults. daf-16 is required for the enhanced survival of arrested larvae, suggesting that the increased longevity is a physiological response to the essential gene inactivation. These results suggest that insulin-signaling pathways play a role in regulation of aging at any stage in life

    Safety justification of healthcare applications using synthetic datasets

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    Background: Increasing numbers of intelligent healthcare applications are developed by analysing big data, on which they are trained. It is necessary to assure that such applications will be safe for patients; this entails validation against datasets. But datasets cannot be shared easily, due to privacy, and consent issues, resulting in delaying innovation. Realistic Synthetic Datasets (RSDs), equivalent to the real datasets, are seen as a solution to this. Objective: To develop the outline for safety justification of an application, validated with an RSD, and identify the safety evidence the RSD developers will need to generate. Method: Assurance case argument development approaches were used, including high level data related risk identification. Result: An outline of the justification of such applications, focusing on the contribution of the RSD. Conclusions: Use of RSD will require specific arguments and evidence, which will affect the adopted methods. Mutually supporting arguments can result in a compelling justification

    Clustering studies of radio-selected galaxies

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    Philosophiae Doctor - PhDWe investigate the clustering of HI-selected galaxies in the ALFALFA survey and compare results with those obtained for HIPASS. Measurements of the angular correlation function and the inferred 3D-clustering are compared with results from direct spatial-correlation measurements. We are able to measure clustering on smaller angular scales and for galaxies with lower HI masses than was previously possible. We calculate the expected clustering of dark matter using the redshift distributions of HIPASS and ALFALFA and show that the ALFALFA sample is somewhat more anti-biased with respect to dark matter than the HIPASS sample. We are able to conform the validity of the dark matter correlation predictions by performing simulations of the non-linear structure formation. Further we examine how the bias evolves with redshift for radio galaxies detected in the the first survey.South Afric

    Tectonostratigraphic controls on pore fluid pressure distribution across the Taranaki Basin, New Zealand

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    Significant variations in pore pressure across the Taranaki Basin, New Zealand, are attributed to changes in lithofacies and structure, usefully illustrated in terms of ten areas that we term geopressure provinces, each displaying individual pore pressure trends. Cretaceous to Early Miocene formations in different parts of the basin can be either normally pressured (near or at hydrostatic) or significantly overpressured (up to 28 MPa) at the same depth. Variations in Eocene–Oligocene facies types and thicknesses both within and between geopressure provinces provide first-order control on the magnitude, distribution and maintenance of overpressure across the basin. Examples of hydraulic compartmentalisation due to sealing faults and stratigraphic architecture are identified within the basin. Deep pore pressure transitions are sealed by diagenetic, structural or stratigraphic mechanisms in different places and are associated with an increase in mudrock volume (reduced permeability) or gas generation. Thus, pore pressure distribution in the Taranaki Basin is controlled by a combination of sediment loading, lithofacies variations, fault zone permeability and structural architecture. This work represents an appraisal of the pore pressure distribution across the whole of a multiphase structurally complex basin, and the approach taken provides a framework for better understanding the distribution of pore fluid pressures and pore fluid migration in other sedimentary basins
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