233 research outputs found

    Spike-and-Slab Priors for Function Selection in Structured Additive Regression Models

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    Structured additive regression provides a general framework for complex Gaussian and non-Gaussian regression models, with predictors comprising arbitrary combinations of nonlinear functions and surfaces, spatial effects, varying coefficients, random effects and further regression terms. The large flexibility of structured additive regression makes function selection a challenging and important task, aiming at (1) selecting the relevant covariates, (2) choosing an appropriate and parsimonious representation of the impact of covariates on the predictor and (3) determining the required interactions. We propose a spike-and-slab prior structure for function selection that allows to include or exclude single coefficients as well as blocks of coefficients representing specific model terms. A novel multiplicative parameter expansion is required to obtain good mixing and convergence properties in a Markov chain Monte Carlo simulation approach and is shown to induce desirable shrinkage properties. In simulation studies and with (real) benchmark classification data, we investigate sensitivity to hyperparameter settings and compare performance to competitors. The flexibility and applicability of our approach are demonstrated in an additive piecewise exponential model with time-varying effects for right-censored survival times of intensive care patients with sepsis. Geoadditive and additive mixed logit model applications are discussed in an extensive appendix

    Life table analysis of Diaphorina citri (Hemiptera: Psyllidae) infesting sweet orange (Citrus sinensis) in SĂŁo Paulo

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    An ecological life table for eggs and nymphs of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) was constructed with data obtained from orange orchards (Citrus sinensis Osbeck) in 2 regions of the State of SĂŁo Paulo, over 4 generations in the period from XI-2006 to V-2007, comprising spring, summer, and fall seasons. Young growing shoots with D. citri eggs present were identifed, and live individuals were counted until adult emergence. No predatory arthropods were observed in association with D. citri eggs and nymphs during the study. The mean parasitism of fourth- and ffth-instar nymphs by Tamarixia radiata Waterston (Hymenoptera: Eulophidae) was 2.3%. The durations of the egg–adult period were similar among the 4 generations, ranging from 18.0 to 24.7 d (at mean temperatures ranging from 21.6 to 26.0 °C) and followed the temperature requirement models obtained in the laboratory for D. citri. However, survival from the egg to the adult stage for the same period varied considerably from 1.7 to 21.4%; the highest mortalities were observed in the egg and small nymphal (frst- to thirdinstar) stages, which were considered to be key phases for population growth of the pest.Uma tabela de vida ecolĂłgica foi construĂ­da para ovos e ninfas de Diaphorina citri Kuwayama (Hemiptera: Psyllidae) com dados obtidos em pomares de laranja (Citrus sinensis Osbeck) em 2 regiĂ”es do estado de SĂŁo Paulo, com 4 geraçÔes, no perĂ­odo de novembro de 2006 a maio de 2007, compreendendo as estaçÔes de primavera, verĂŁo e outono. Ramos jovens em crescimento com a presença de ovos de D. citri foram identificados e os indivĂ­duos vivos foram contados atĂ© a emergĂȘncia dos adultos. Nenhum predador foi observado associado a ovos e ninfas de D. citri durante o estudo. A taxa mĂ©dia de parasitismo de ninfas de quarto e quinto Ă­nstares por Tamarixia radiata Waterson (Hymenoptera: Eulophidae) foi de 2.3%. A duração do perĂ­odo de ovo a adulto foi semelhante entre as quatro geraçÔes, variando de 18.0 a 24.7 dias (com temperaturas mĂ©dias de 21.6 a 26.0 °C) e seguiram os modelos de exigencias tĂ©rmicas obtidas em laboratĂłrio para D. citri. Todavia, a sobrevivencia de ovo atĂ© o estĂĄgio adulto variou consideravelmente para o mesmo perĂ­odo, de 1.7 a 21.4%, sendo que as maiores mortalidades foram observadas nos estĂĄgios de ovos e ninfas pequenas (de primeiro a terceiro Ă­nstares), as quais foram consideradas fases chaves para o crescimento populacional desta praga.info:eu-repo/semantics/publishedVersio

    Data mining in collections: from epidemiology to demography

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    Random collection surveys can be a rich source of data on the material state of a collection. However, random surveys do not necessarily provide data on the causes of degradation of collection items, which is useful in terms of resource allocation. For this, the reliability theory provides us with the required concepts. Using appropriate survey methods and statistical methods of data analysis, the so obtained observational ‘epidemiology’ data has revealed risk factors that can lead to such degradation. We identified patterns in the observed data that corroborated experimental research findings and enabled us to carry out ‘demographic’ modelling of the dynamics of future change in the surveyed collection for the case study of the Amsterdam City Archives. The study shows how, using appropriate methods of collection surveying, empirical and modelling studies of real collections can be successfully integrated, leading to useful evidence supporting collection care decision making

    Classifying degraded modern polymeric museum artefacts by their smell

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    Volatile organic compound (VOC) analysis is a successful method for diagnosing medical conditions such as Alzheimer’s disease. However, despite its relevance to heritage, it has found little application in museums. We report the first use of VOC analysis to ‘diagnose’ degradation in modern polymeric museum artefacts. Modern polymers are increasingly found in museum collections but pose serious conservation difficulties due to unstable and widely varying formulations. Solid-phase microextraction gas chromatography/mass spectrometry and linear discriminant analysis were used to classify samples according to the length of time they had been artificially degraded. Classification accuracies of 50-83% were obtained after validation with separate test sets. The method was applied to three artefacts from collections at Tate to detect evidence of degradation. This novel approach could be used for any material in heritage collections and more widely in the field of polymer degradation

    Diseño de una nueva crepina para reducir la caida de presión en filtros de arena

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    La filtración es necesaria para evitar la obturación de los emisores, que es el principal problema del riego por goteo. Sin embargo, los filtros necesitan presiones elevadas que estån relacionadas con un mayor consumo energético. Estudios anteriores han mostrado que la caída de presión en los filtros de arena, considerados como los eståndares en riego por goteo, se localiza principalmente en el drenaje. El principal objetivo del trabajo fue diseñar un nuevo modelo de crepina que redujera la caída de presión en el filtro. Esta nueva crepina tiene mayores pasajes a la salida del drenaje, estå rodeada con un medio granular de mayor conductividad hidråulica y modifica la curvatura del flujo por encima de la crepina. La nueva crepina fue construida y ensayada en condiciones de filtrado y contralavado, con y sin medio filtrante, en un filtro de laboratorio escalado a partir de un filtro comercial. Esta nueva crepina redujo considerablemente la caída de presión con respecto el diseño comercial. Se desarrolló también un modelo CFD para analizar con detalle las zonas donde se consigue la reducción observada.Filtration is mandatory for preventing emitter clogging, which is the main drawback of microirrigation. However, microirrigation filters have high pressure requirements, which in turn are related to higher energy consumption. Previous studies have shown that pressure loss in sand media filters, which are usually considered the standard for microirrigation, are mainly located in the filter underdrain. The main objective was to design a new underdrain that could reduce sand media filter pressure drop. The new underdrain has wider passages to the underdrain outlet, is surrounded with a granular medium with higher hydraulic conductivity and it modifies the flow curvature above the underdrain. The new underdrain was built and tested under filtration and backwashing conditions and with and without filter bed using a laboratory filter which was scaled from a commercial filter. The new underdrain considerably reduced pressure loss compared with a commercial filter. A CFD model was developed for further study those filter areas where the underdrain achieved a higher reduction of pressure drop

    Sampling and distribution pattern of Trioza erytreae Del Guercio, 1918 (Hemiptera: Triozidae) in citrus orchard

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    Developing efficient sampling protocols is essential to monitor crop pests. One vector of the citrus disease HLB, the African citrus psyllid Trioza erytreae Del Guercio, 1918 (Hemiptera: Triozidae), currently threatens the lemon industry throughout the Mediterranean region. In this work, a pool of sampling methods devoted to monitoring the population of T. erytreae was compared, its spatial distribution in the orchard was assessed, and the minimum sampling effort for the best sampling method was estimated. Three lemon orchards in North-western Portugal were sampled for one year using two types of yellow sticky traps (standard yellow and fluorescent Saturn yellow), B-vac sampling and sweep net sampling. The method that best performed, in terms of cost-efficiency, was the yellow sticky traps. The two colours of the sticky traps tested did not yield a significantly different number of catches. The spatial distribution throughout the orchards was found to be aggregated towards the borders. A minimum of three sticky traps per hectare was found to be enough to estimate the population at 90% accuracy for the mean during the outbreak. These results should help to monitor and anticipate outbreaks that may even colonize neighbour orchards. Studies on the local dispersion patterns of T. erytreae throughout the orchard are mandatory to further refine and optimize efficient monitoring protocols.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal), for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020) and to the project PRE-HLB-Preventing HLB epidemics for ensuring citrus survival in Europe (H2020-SFS-2018-2 Topic SFS-05-2018-2019-2020, proj. No. 817526).info:eu-repo/semantics/publishedVersio

    An effector from the Huanglongbing-associated pathogen targets citrus proteases

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    The citrus industry is facing an unprecedented challenge from Huanglongbing (HLB). All cultivars can be affected by the HLB-associated bacterium ‘Candidatus Liberibacter asiaticus’ (CLas) and there is no known resistance. Insight into HLB pathogenesis is urgently needed in order to develop effective management strategies. Here, we use Sec-delivered effector 1 (SDE1), which is conserved in all CLas isolates, as a molecular probe to understand CLas virulence. We show that SDE1 directly interacts with citrus papain-like cysteine proteases (PLCPs) and inhibits protease activity. PLCPs are defense-inducible and exhibit increased protein accumulation in CLas-infected trees, suggesting a role in citrus defense responses. We analyzed PLCP activity in field samples, revealing specific members that increase in abundance but remain unchanged in activity during infection. SDE1-expressing transgenic citrus also exhibit reduced PLCP activity. These data demonstrate that SDE1 inhibits citrus PLCPs, which are immune-related proteases that enhance defense responses in plants

    Orange jasmine as a trap crop to control Diaphorina citri

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    [EN] Novel, suitable and sustainable alternative control tactics that have the potential to reduce migration of Diaphorina citri into commercial citrus orchards are essential to improve management of huanglongbing (HLB). In this study, the effect of orange jasmine (Murraya paniculata) as a border trap crop on psyllid settlement and dispersal was assessed in citrus orchards. Furthermore, volatile emission profiles and relative attractiveness of both orange jasmine and sweet orange (Citrus¿×¿aurantium L., syn. Citrus sinensis (L.) Osbeck) nursery flushes to D. citri were investigated. In newly established citrus orchards, the trap crop reduced the capture of psyllids in yellow sticky traps and the number of psyllids that settled on citrus trees compared to fallow mowed grass fields by 40% and 83%, respectively. Psyllids were attracted and killed by thiamethoxam-treated orange jasmine suggesting that the trap crop could act as a `sinkÂż for D. citri. Additionally, the presence of the trap crop reduced HLB incidence by 43%. Olfactometer experiments showed that orange jasmine plays an attractive role on psyllid behavior and that this attractiveness may be associated with differences in the volatile profiles emitted by orange jasmine in comparison with sweet orange. Results indicated that insecticide-treated M. paniculata may act as a trap crop to attract and kill D. citri before they settled on the edges of citrus orchards, which significantly contributes to the reduction of HLB primary spread.This work was supported by Fund for Citrus Protection (Fundecitrus) and by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) (Proc. 2015/07011-3). We thank Moacir Celio Vizone, Felipe Marinho Martini and Joao Pedro Ancoma Lopes for technical support with experiments. Furthermore, we thank Cambuhy Agricola Ltda. and University of Araraquara (Uniara) for providing the areas in which the field experiments were performed. Second author received scholarship from National Council for Scientific and Technological Development (CNPq)/Brazil (Proc. 300153/2011-2).Tomaseto, AF.; Marques, RN.; Fereres, A.; Zanardi, OZ.; Volpe, HXL.; AlquĂ©zar-GarcĂ­a, B.; Peña, L.... (2019). Orange jasmine as a trap crop to control Diaphorina citri. Scientific Reports. 9:1-11. https://doi.org/10.1038/s41598-019-38597-5S1119BovĂ©, J. M. Huanglongbing: a destructive, newly-emerging, century-old disease of citrus. J Plant Pathol. 88, 7–37 (2006).Alvarez, S., Rohrig, E., SolĂ­s, D. & Thomas, M. H. Citrus greening disease (Huanglongbing) in Florida: economic impact, management and the potential for biological control. Agric. Res. 5, 109–118 (2016).Belasque, J. Jr. et al. Lessons from huanglongbing management in SĂŁo Paulo state, Brazil. J. Plant Pathol. 92, 285–302 (2010).Boina, D. R., Meyer, W. L., Onagbola, E. O. & Stelinski, L. L. Quantifying dispersal of Diaphorina citri (Hemiptera: Psyllidae) by immunomarking and potential impact of unmanaged groves on commercial citrus management. Environ. Entomol. 38, 1250–8 (2009).Lewis-Rosenblum, H., Martini, X., Tiwari, S. & Stelinski, L. L. Seasonal movement patterns and long-range dispersal of Asian citrus psyllid in Florida citrus. J. Econ. Entomol. 108, 3–10 (2015).Hall, D. G. & Hentz, M. G. Seasonal flight activity by the Asian citrus psyllid in east central Florida. Entomol. Exp. Appl. 139, 75–85 (2011).Tomaseto, A. F., Krugner, R. & Lopes, J. R. S. Effect of plant barriers and citrus leaf age on dispersal of Diaphorina citri (Hemiptera: Liviidae). J. Appl. Entomol. 140, 91–102 (2016).Gottwald, T. R. Current epidemiological understanding of citrus huanglongbing. Annu. Rev. Phytopathol. 48, 119–139 (2010).Bassanezi, R. B. et al. Efficacy of area-wide inoculum reduction and vector control on temporal progress of huanglongbing in young sweet orange plantings. Plant Dis. 97, 789–796 (2013).SĂ©tamou, M. & Bartels, D. W. Living on the edges: spatial niche occupation of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in citrus groves. PLoS One 10, 1–21 (2015).Gottwald, T., Irey, M., Gast, T. & Parnell, S. Spatio-temporal analysis of an HLB epidemic in Florida and implications for spread. In Proceedings of the 17 th Conference of International Organization of Citrus Virologists, IOCV, University of California, Riverside, CA, 84–97 (2010).Shelton, A. M. & Badenes-Perez, F. R. Concepts and applications of trap cropping in pest management. Annu. Rev. Entomol 51, 285–308 (2006).Hokkanen, H. M. T. Trap cropping in pest management. Annu. Rev. Entomol. 36, 119–138 (1991).Stern, V. M., Mueller, A., Sevacherian, V. & Way, M. Lygus bug control in cotton through alfalfa interplanting. Calif. Agric. 8–10 (1969).Godfrey, L. D. & Leigh, T. F. Alfalfa harvest strategy effect on lygus bug (Hemiptera: Miridae) and insect predator population density: Implications for use as trap crop in cotton. Environ. Entomol. 23, 1106–1118 (1994).Gonsalves, D. & Ferreira, S. Transgenic papaya: a case for managing risks of Papaya ringspot virus in Hawaii. Plant Heal. Prog. 1–6, https://doi.org/10.1094/PHP-2003-1113-03-RV (2003)Aubert, B. Trioza erytheae del Guercio and Diaphorina citri Kuwayama (Homoptera: Psylloidea), the two vectors of citrus greening disease: biological aspects and possible control strategies. Fruits 42, 149–162 (1987).Leong, S. C. T., Fatimah, A., Beattie, A., Heng, R. K. J. & King, W. S. Influence of host plant species and flush growth stage on the Asian citrus psyllid, Diaphorina citri Kuwayama. Am. J. Agric. Biol. Sci. 6, 536–543 (2011).Patt, J. M. & SĂ©tamou, M. Responses of the Asian citrus psyllid to volatiles emitted by the flushing shoots of its rutaceous host plants. Environ. Entomol. 39, 618–24 (2010).Damsteegt, V. D. et al. Murraya paniculata and related species as potential hosts and inoculum reservoirs of ‘Candidatus Liberibacter asiaticus’, causal agent of huanglongbing. Plant Dis. 94, 528–533 (2010).Lopes, S. A. et al. Liberibacters associated with orange jasmine in Brazil: Incidence in urban areas and relatedness to citrus liberibacters. Plant Pathol. 59, 1044–1053 (2010).Cifuentes-Arenas, J. C. Huanglongbing e Diaphorina citri: Estudos das relaçÔes patĂłgeno-vetor-hospedeiro. Ph.D. Thesis. Faculdade de CiĂȘncias AgrĂĄrias e VeterinĂĄrias/Universidade Estadual Paulista (UNESP), Jaboticabal, SP, Brazil. 1–133 (2017).Morilla, G. et al. Pepper (Capsicum annuum) is a dead-end host for Tomato yellow leaf curl virus. Phytopathology 95, 1089–1097 (2005).Midega, C. A. O., Pittchar, J. O., Pickett, J. A., Hailu, G. W. & Khan, Z. R. A climate-adapted push-pull system effectively controls fall armyworm, Spodoptera frugiperda (J. E. Smith), in maize in East Africa. Crop Prot. 105, 10–15 (2018).Miranda, M. P. et al. Processed kaolin affects the probing and settling behavior of Diaphorina citri (Hemiptera: Liviidae). Pest Manag. Sci. 74, 1964–1972 (2018).Kobori, Y., Nakata, T., Ohto, Y. & Takasu, F. Dispersal of adult Asian citrus psyllid, Diaphorina citri Kuwayama (Homoptera: Psyllidae), the vector of citrus greening disease, in artificial release experiments. Appl. Entomol. Zool. 46, 27–30 (2011).SĂ©tamou, M. et al. Diurnal patterns of flight activity and effects of light on host finding behavior of the Asian citrus psyllid. J. Insect Behav. 25, 264–276 (2012).Wenninger, E. J., Stelinski, L. L. & Hall, D. G. Roles of olfactory cues, visual cues, and mating status in orientation of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) to four different host plants. Environ. Entomol. 38, 225–234 (2009).Miranda, M. P., Dos Santos, F. L., Felippe, M. R., Moreno, A. & Fereres, A. Effect of UV-blocking plastic films on take-off and host plant finding ability of Diaphorina citri (Hemiptera: Liviidae). J. Econ. Entomol. 108, 245–251 (2015).Visser, J. H. Host odor perception in phytophagous insects. Annu. Rev. Entomol. 31, 121–144 (1986).Robbins, P. S., Alessandro, R. T., Stelinski, L. L. & Lapointe, S. L. Volatile profiles of young leaves of Rutaceae spp. varying in susceptibility to the Asian citrus psyllid (Hemiptera: Psyllidae). Florida Entomol. 95, 774–776 (2012).Fancelli, M. et al. Attractiveness of host plant volatile extracts to the Asian citrus psyllid, Diaphorina citri, is reduced by terpenoids from the non-host cashew. J. Chem. Ecol. 44, 397–405 (2018).AlquĂ©zar, B. et al. ÎČ-caryophyllene emitted from a transgenic Arabidopsis or chemical dispenser repels Diaphorina citri, vector of Candidatus Liberibacters. Sci. Rep. 7, 5639 (2017).Jones, R. A. C. Effects of cereal borders, admixture with cereals and plant density on the spread of bean yellow mosaic potyvirus into narrow‐leafed lupins (Lupinus angustifolius). Ann. Appl. Biol. 122, 501–518 (1993).Beloti, V. H., Alves, G. R., Coletta-Filho, H. D. & Yamamoto, P. T. The Asian citrus psyllid host Murraya koenigii is immune to citrus huanglongbing pathogen ‘Candidatus Liberibacter asiaticus’. Phytopathology 108, 1089–1094 (2018).Walter, A. J., Duan, Y. & Hall, D. G. Titers of ‘Ca. Liberibacter asiaticus’ in Murraya paniculata and Murraya-reared Diaphorina citri are much lower than in Citrus and Citrus-reared psyllids. HortScience 47, 1449–1452 (2012).Walter, A. J., Hall, D. G. & Duan, Y. P. Low incidence of ‘Candidatus Liberibacter asiaticus’ in Murraya paniculata and associated Diaphorina citri. Plant Dis. 96, 827–832 (2012).Ammar, E.-D. D., Ramos, J. E., Hall, D. G., Dawson, W. O. & Shatters, R. G. Acquisition, replication and inoculation of Candidatus Liberibacter asiaticus following various acquisition periods on huanglongbing-infected citrus by nymphs and adults of the Asian citrus psyllid. PLoS One 11, e0159594 (2016).Inoue, H. et al. Enhanced proliferation and efficient transmission of Candidatus Liberibacter asiaticus by adult Diaphorina citri after acquisition feeding in the nymphal stage. Ann. Appl. Biol. 155, 29–36 (2009).Pelz-Stelinski, K. S., Brlansky, R. H., Ebert, T. A. & Rogers, M. E. Transmission parameters for Candidatus Liberibacter asiaticus by Asian citrus psyllid (Hemiptera: Psyllidae). J. Econ. Entomol. 103, 1531–1541 (2010).Canale, M. C. et al. Latency and persistence of ‘Candidatus Liberibacter asiaticus’ in its psyllid vector, Diaphorina citri (Hemiptera: Liviidae). Phytopathology 107, 264–272 (2017).Li, W., Hartung, J. S. & Levy, L. Quantitative real-time PCR for detection and identification of Candidatus Liberibacter species associated with citrus huanglongbing. J. Microbiol. Methods 66, 104–115 (2006).Nakata, T. Effectiveness of micronized fluorescent powder for marking citrus psyllid. Diaphorina citri. Appl. Entomol. Zool. 43, 33–36 (2008).Tomaseto, A. F. et al. Environmental conditions for Diaphorina citri Kuwayama (Hemiptera: Liviidae) take-off. J. Appl. Entomol. 142, 104–113 (2018).Paris, T. M., Croxton, S. D., Stansly, P. A. & Allan, S. A. Temporal response and attraction of Diaphorina citri to visual stimuli. Entomol. Exp. Appl. 155, 137–147 (2015).Zanardi, O. Z. et al. Putative sex pheromone of the Asian citrus psyllid, Diaphorina citri, breaks down into an attractant. Sci. Rep. 8, 455 (2018).Metsalu, T. & Vilo, J. ClustVis: A web tool for visualizing clustering of multivariate data using Principal Component Analysis and heatmap. Nucleic Acids Res. 43, W566–W570 (2015).Fournier, D. A. et al. AD Model Builder: using automatic differentiation for statistical inference of highly parameterized complex nonlinear models. Optim. Methods Softw. 27, 233–249 (2012).Bates, D., MĂ€chler, M., Bolker, B. & Walker, S. Fitting linear mixed-effects models using lme4. J. Stat. Softw. 67, 1–48 (2015).Nelder, J. A. & Wedderburn, R. W. M. Generalized linear models. J. R. Stat. Soc. 135, 370–384 (1972).DemĂ©trio, C. G. B., Hinde, J. & Moral, R. A. In Ecological Modelling Applied to Entomology (eds Ferreira, C. P. & Godoy, W. A. C.) 219–259 (Springer, 2014).Lenth, R. V. Least-Squares Means: the R package lsmeans. J. Stat. Softw. 69, (2016).R Core Team R: A language and environment for statistical computing. 2015. R Foundation for Statistical Computing, Vienna, Austria (2015). Available at, http://www.r-project.org/ . (Accessed: 20th July 2017)
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