共查询到20条相似文献,搜索用时 31 毫秒
1.
Bas Engel Jantien Backer Willem Buist 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(1):83-100
A model is presented to evaluate the accuracy of diagnostic tests from data from individuals that are repeatedly tested in
time. Repeated measurements from three diagnostic tests for foot-and-mouth disease, applied to vaccinated and experimentally
infected cattle, were analyzed. At any time the true disease status of the individuals was unknown, i.e., no gold standard
was available. The model allows for correlation between repeated test results, in consequence of the underlying structure
for the unknown true disease status, but also by the distribution of the test results conditional upon true disease status.
The model also allows for dependence between the different diagnostic tests conditional upon true disease status. Prior information
about the structure of the prevalence and the specificity of the tests was incorporated in a Bayesian analysis. Posterior
inference was carried out with Markov chain Monte Carlo. Simulated data were analyzed to gain insight into the performance
of the posterior Bayesian inference. The simulated data are typical for the expensive and, therefore, modestly sized infection
experiments that are conducted under controlled conditions. 相似文献
2.
Ling Xu Timothy Hanson Edward J. Bedrick Carla Restrepo 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(3):308-326
Multiple comparisons are widely used to compare gross features of distributions across populations. However, often a scientific hypothesis is more easily couched in terms of more focused null and alternative statistical hypotheses. For example, among distributions exhibiting clusters of continuous measurements across strata, are there clusters of measurements similar in terms of location, spread, or weight? We propose testing such hypotheses using a sequence of nested finite mixture models. Reasonable, data-driven priors are suggested based on estimates of the sample spreads and midpoints. Formal hypothesis testing is carried out through the computation of Bayes factors. The method is illustrated on Holling’s (Ecological Monographs 62:447–502, 1992) forest and prairie bird body mass data, and data on the time-to-abortion in dairy cows. Supplemental simulations are available online. 相似文献
3.
Richard Huggins Wen-Han Hwang 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(2):198-208
Logistic models for capture probabilities that depend on covariates are effective if the covariates can be measured exactly.
If there is measurement error so that a surrogate for the covariate is observed rather than the covariate itself, simple adjustments
may be made if the parameters of joint distribution of the covariate and the surrogate are known. Here we consider the case
when a surrogate is observed whenever an individual is captured and the parameters must also be estimated from the data. An
estimating equation regression calibration approach is developed and it is illustrated on a real dataset where the surrogate
is an individual bird’s wing-length, which varies from occasion to occasion. 相似文献
4.
Yielding sound estimates of survival according to age in wild populations where senescence or other age-related variations
may occur is very important to management decision makers, and remains challenging. This paper proposes to use penalized maximum
likelihood to obtain smooth estimates of annual survival probabilities across age in populations of wild animals followed
by capture–recapture. We propose to use two different types of smoothing penalties, and we use ν-fold cross-validation to select the best value of the tuning parameter for the intensity of smoothing. We then assess the
accuracy of the method by a simulation study with two different shapes of the relationship between age and survival, and we
conclude that a careful use of this method provides reliable noise-free estimates of age-specific annual survival. We apply
this procedure to the motivating data from a population of roe deer known to exhibit a marked decrease of survival with age,
and we compare our results with those previously published on this population. 相似文献
5.
Steffen Unkel Abdel Hannachi Nickolay T. Trendafilov Ian T. Jolliffe 《Journal of Agricultural, Biological & Environmental Statistics》2011,16(3):319-338
In this paper, a new approach to independent component analysis (ICA) for three-way data is considered. The rotational freedom
of the three-mode component analysis (Tucker3) model is exploited to implement ICA in one mode of the data. The performance
of the proposed approach is evaluated by means of numerical experiments. An illustration with real data from atmospheric science
is presented, where the first mode is spatial location, the second is time and the third is a set of different meteorological
variables representing geopotential heights at various vertical pressure levels. The results show that the three-mode decomposition
finds spatial patterns of climate anomalies which can be interpreted in a meteorological sense and as such gives an insightful
low-dimensional representation of the data. 相似文献
6.
7.
Paweł Wójcik Hüseyin Akgül İsmail Demirtaş Cumhur Sarısu Mehmet Aksu Hamide Gubbuk 《Journal of plant nutrition》2013,36(9):1453-1465
The aim of the study was to examine impact of preharvest sprays of calcium (Ca) and sucrose on splitting and quality of ‘Burlat’ sweet cherry fruit. The study was carried out during 2009–2010 in Poland and Turkey, on mature trees planted at a moderate density on coarse- and medium-textured soils. Sweet cherries were sprayed with calcium chloride (CaCl2) and/or sucrose at a rate of 5 kg of each material per ha, using ca. 1000 L of water. In Poland, sprays of CaCl2 and/or sucrose were applied 8–14 h before each rain, starting 21 d before harvest, whereas in Turkey the spray treatments were made schematically: 7, 14 and 21 d before harvest. Sprays of water were treated as the control. The results showed that preharvest sprays of CaCl2 and/or sucrose did not affect yield, mean fruit weight, and fruit acidity. Sprays of CaCl2 increased fruit Ca status, and simultaneously reduced fruit cracking in an orchard or laboratory test. In the trial performed in Turkey, part of fruit sprayed with CaCl2 (<5%) had spray deposit on the peel. Sucrose sprays did not affect fruit cracking. In one year of the study in Turkey, sucrose sprays increased soluble solids concentration of fruit; however, part of fruit treated with sucrose (<2%) had spray deposit on the skin. 相似文献
8.
Hai Liu Lorenzo Ciannelli Mary Beth Decker Carol Ladd Kung-Sik Chan 《Journal of Agricultural, Biological & Environmental Statistics》2011,16(2):185-201
There is increasing scientific interest in studying the spatial distribution of species abundance in relation to environmental
variability. Jellyfish in particular have received considerable attention in the literature and media due to regional population
increases and abrupt changes in distribution. Jellyfish distribution and abundance data, like many biological datasets, are
characterized by an excess of zero counts or nonstationary processes, which hampers their analyses by standard statistical
methods. Here we further develop a recently proposed statistical framework, the constrained zero-inflated generalized additive
model (COZIGAM), and apply it to a spatio-temporal dataset of jellyfish biomass in the Bering Sea. Our analyses indicate systematic
spatial variation in the process that causes the zero inflation. Moreover, we show strong evidence of a range expansion of jellyfish
from the southeastern to the northwestern portion of the survey area beginning in 1991. The proposed methodologies could be
readily applied to ecological data in which zero inflation and spatio-temporal nonstationarity are suspected, such as data
describing species distribution in relation to changes of climate-driven environmental variables. Some supplemental materials
including an animation of jellyfish annual biomass and web appendices are available online. 相似文献
9.
10.
Roger Pradel Rémi Choquet Mauricio A. Lima Joseph Merritt Laurent Crespin 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(2):248-258
The direct estimation and modeling of population growth rate from capture–recapture data has now seen a number of applications.
However, the original model cannot accommodate heterogeneous capture probabilities. While studying a population of small mammals
Peromyscus maniculatus, we became concerned that the peak of population size may be estimated too late in the year because of heterogeneous catchability.
Hence, we developed a variation of the original model with a finite number of catchability classes. The results obtained with
the new model are more in agreement with the known biology of this population. A bibliographic appendix and computer code
are available online. 相似文献
11.
Dr Silke Velty Jürgen Augustin Axel Behrendt Jutta Zeitz 《Archives of Agronomy and Soil Science》2013,59(6):629-643
Abstract The present study aims at assessing the effect of using the effluent of a wastewater treatment plant as an alternative measure for rewetting nutrient-rich fen soils over the growing season on the emission of greenhouse gas (GHG) and at discussing possible changes in the greenhouse potential as a result of this practice. In order to allow a discussion on GHG based on integrated CH4, N2O, and CO2 flux rates, fluxes were measured in our lysimeter study using the chamber methodology from May to December in 2003 and 2004. The study compares the gaseous fluxes of fen soils in lysimeters treated with the effluent and/or freshwater for rewetting. Only freshwater was applied to the control lysimeter. The source of water hardly had any statistically significant effect on trace gas fluxes. However, there was a trend towards higher CH4 emissions at the effluent lysimeters compared to the control lysimeter. Effluent usage did not decrease the greenhouse effect at the same rate, which could be observed at the control. Nevertheless, regarding gaseous emissions the use of effluents could prove to be a solution to the current problem of today's major peat oxidation and fen soil loss by drainage. 相似文献
12.
M. Khayyat A. Tehranifar M. Zaree Z. Karimian M. H. Aminifard M. R. Vazifeshenas 《Journal of plant nutrition》2013,36(9):1387-1393
The present research was carried out to investigate the effects of potassium nitrate on pomegranate fruit quality. Treatments were: 1) control, distilled water was used; 2) potassium nitrate 250 mg L-1 plus Tween-20 and 3) potassium nitrate 500 mg L-1 plus Tween-20. All treatments were sprayed on fruits with a diameter of 30 mm. Juice, peel, seed characters, and fruit quality components were evaluated when fruits were harvested. Results indicated that 250 mg L-1 potassium treatment increased juice volume and weight compared with the control and the 500 mg L-1 K treatments. As the potassium nitrate level increased, aril length and diameter decreased. Although there was not a significant difference among treatments on titrable acidity and pH contents of fruits, the highest total soluble solids and vitamin C were obtained in the 250 mg L-1 potassium nitrate treatment when compared with the others. These findings show that applied potassium nitrate significantly influences fruit quality of pomegranate when fruit are in the beginning stages of growth and development. 相似文献
13.
Paweł Wójcik Hamide Gubbuk Hüseyin Akgül Esma Gunes Kadir Ucgun Hakkı Koçal 《Journal of plant nutrition》2013,36(13):1914-1925
The aim of the study was to examine impact of foliar titanium (Ti) sprays on vegetative and reproductive response of apple (Malus domestica Borkh.) trees under conditions of low soil availability of iron (Fe), manganese (Mn), and zinc (Zn). The experiment was conducted during 2005–2006 at a Experimental Station in Isparta region, Turkey, on mature ‘Granny Smith’ apple trees/M.9, planted at a spacing of 3.5 × 1.5 m, on fine-textured soil with neutral reaction, medium status of organic matter, high amounts of available phosphorus (P), potassium (K), and magnesium (Mg), and low availability of Fe, Mn, and Zn. The trees were sprayed with Ti-ascorbate at the green and pink bud stage, petal fall, and 3, 6, and 9 weeks after full bloom, at a rate of 3 g Ti ha?1 per spray. The efficiency of Ti sprays was compared to combined sprays of Fe, Mn, and Zn [chelated with ethylenediaminetetraacetic acid (EDTA)], applied at the same terms as Ti sprays, at rate of 36 g, 36 g and 24 g per spray, respectively. Trees unsprayed with Ti, Fe, Mn, and Zn served as the control. It was shown that summer leaf Ti concentrations of the trees untreated with Ti were high, varying from 34 to 36 mg kg?1 dry matter. Foliar Ti sprays increased leaf status of this nutrient but they had no effect on nutrition of essential macro- and microelements, tree vigor, and fruit yield. Mean apple weight, coloring, firmness, soluble solids concentration, and titratable acidity of fruit were not also influenced by Ti sprays. Foliar sprays of Fe, Mn, and Zn improved leaf status of nitrogen (N), Mg, Fe, Mn, and Zn; leaves of the trees sprayed with those micronutrients were also greener, and contained more Fe2+ than those of the control plants. Combined sprays of Fe, Mn, and Zn improved tree vigor and fruit yield. 相似文献
14.
Dawn B. Woodard Robert L. Wolpert Michael A. O’Connell 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(2):209-227
We develop a method for multiscale estimation of pollutant concentrations, based on a nonparametric spatial statistical model.
We apply this method to estimate nitrate concentrations in groundwater over the mid-Atlantic states, using measurements gathered
during a period of 10 years. A map of the fine-scale estimated nitrate concentration is obtained, as well as maps of the estimated
county-level average nitrate concentration and similar maps at the level of watersheds and other geographic regions. The fine-scale
and coarse-scale estimates arise naturally from a single model, without refitting or ad hoc aggregation. As a result, the
uncertainty associated with each estimate is available, without approximations relying on high spatial density of measurements
or parametric distributional assumptions. 相似文献
15.
《Journal of plant nutrition》2013,36(10):2151-2159
ABSTRACT The impact that nitrogen (N), phosphorus (P), and potassium (K) application rates on the sulfur (S) fractions in leaves and fruits of greenhouse-grown cucumbers plants (Cucumis sativus L. cv. Brunex) are presented. The treatments were as follows: N (N1=5 g NO3NH4/m2, N2=10 g NO3NH4/m2, N3=20 g NO3NH4/m2, N4=40 g NO3NH4/m2), two levels of P (P1=8 g H3PO4/m2 and P2=16 g H3PO4/m2), and two levels of K (K1=20 g K2SO4/m2 and K2=40 g K2SO4/m2). The foliar and fruit contents were determined for total S, organic S and sulfate. The influence of the N treatments on the total S (St: organic S +sulfate) concentration, proved significant, showing a progressive increase in the leaf and fruit concentrations. In the leaves, the P slightly diminished the St concentration but values in the fruits did not appreciably differ from control. The K dosage did not cause the St concentration to differ from that of P, although in the fruit a slightly lower St concentration appeared in the K2 treatment. The response of the organic-S concentration in the leaves resembled that of St, and thus organic S should not be used as a diagnostic method for S status. In the relationship SO4 2-/St, the SO4 2- concentration proved more influential than did the St form, providing a more accurate representation of the potential status of this nutrient in the plant. 相似文献
16.
17.
Koranda M Schnecker J Kaiser C Fuchslueger L Kitzler B Stange CF Sessitsch A Zechmeister-Boltenstern S Richter A 《Soil biology & biochemistry》2011,43(3):551-558
Plant roots strongly influence C and N availability in the rhizosphere via rhizodeposition and uptake of nutrients. This study aimed at investigating the effect of resource availability on microbial processes and community structure in the rhizosphere. We analyzed C and N availability, as well as microbial processes and microbial community composition in rhizosphere soil of European beech and compared it to the bulk soil. Additionally, we performed a girdling experiment in order to disrupt root exudation into the soil. By this novel approach we were able to demonstrate that enhanced resource availability positively affected N mineralization and hydrolytic enzyme activities in the rhizosphere, but negatively affected nitrification rates and oxidative enzyme activities, which are involved in the degradation of soil organic matter. Both rhizosphere effects on N mineralization and oxidative enzyme activities disappeared in the girdling treatment. Microbial community structure in the rhizosphere, assessed by phospholipid fatty acid analysis, differed only slightly from bulk soil but was markedly altered by the girdling treatment, indicating additional effects of the girdling treatment beyond the reduction of root exudation. Differences in oxidative enzyme activities and nitrification rates between rhizosphere soil and bulk soil, however, suggest considerable differences in the (functional) microbial community composition. 相似文献
18.
Dhara Patel 《Journal of plant nutrition》2014,37(14):2209-2226
Increased alkalinity caused reduction in growth of Jatropha curcas plant. This experiment was designed to test the efficacy of beneficial microbes and vermicompost individually and in combinations to alleviate the stressful effect of alkaline stress on growth of Jatropha. Plants inoculated with bacterial consortia had significantly increase in vegetative growth parameters. Soil analysis showed increase in total organic carbon (TOC) by 68% compared to soil before plantation treated with Bacterial consortia + vermicompost. Nitrogen (N) and phosphorus (P) content in the soil was increased by 25% and 84% before plantation treated with Bacterial consortia. Maximum uptake of potassium (K) and sodium (Na) content was observed in consortia. Plant analysis showed that consortia could increase uptake of micronutrients compared to control and other treatments. It can be concluded that multispecies bacterial consortia alone or in combination with mycorrhiza and vermicompost can reduce alkaline stress and enhances the seed germination potential, vegetative growth, and nutrient status of soil. 相似文献
19.
The aim of the study was to examine effects of postharvest sprays of nitrogen (N), boron (B), and zinc (Zn) on reproductive response of sweet cherry (Prunus avium L.) trees, fruit quality and plant nutrition. The experiment was conducted during 2007–2009 in central Poland on mature ‘Burlat’ sweet cherry trees/F12, grown on a coarse-textured soil with low level of organic matter, and optimal soil reaction. Soil status of phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), Zn and copper (Cu) was optimal, whereas B – low. Sweet cherry trees were sprayed with boric acid-B, ethylenediaminetetraacetic acid (EDTA)-Zn, and urea-N at 30–40 d prior to initiation of leaf fall according to following schema: i) spray of N at a rate of 23 kg ha?1; ii) spray of B and Zn at a dose of 1.1 kg ha?1 and 0.5 kg ha?1, respectively; and iii) spray of N, B and Zn at the same rates as in the above spray combinations. The trees sprayed with water served as the control. The results showed that fall spray treatments had no influence on cold damage of flower buds, plant N status and soluble solids concentration in fruit. Postharvest spray of N and combined spray of N, B and Zn injured leaves in the fall but did not cause defoliation. Sprays of B and Zn with or without N increased status of Zn and B in fall leaves, and B in flowers and midsummer leaves. Those sprays also improved fruit set and yield. In one out of two years of the study, fall sprays of N with or without B and Zn decreased mean fruit weight. The above results indicate that only leaf-applied B in the fall improved reproductive response of sweet cherry trees. It is concluded that under conditions of B shortage in a soil and/or plant tissues, postharvest B sprays can be recommended in sweet cherry orchards to improve reproductive growth of the trees. 相似文献
20.
The aim of the study was to examine effect of preharvest sprays of a mixture of calcium (Ca) formate, Ca-acetate, Ca-chloride (CaCl2) and Ca-nitrate [Ca(NO3)2] on quality and apple storability. The experiment was conducted during 2008–2009 at the Experimental Station of the Research Institute of Horticulture in Skierniewice, Poland, on mature ‘Jonagold’ apple trees/M.26, planted at a moderate density on a coarse-textured soil with low status of organic matter and abundant in exchangeable Ca. Apple trees were sprayed with Ca, 7 times per season, at 2-week intervals, starting 3 weeks after blooming. In the spray treatments a mixture of Ca-formate, Ca-acetate, CaCl2 and Ca(NO3)2 (as Insol Wap fertilizer), CaCl2 or Ca(NO3)2 were used at rates of 7.3 kg Ca, 11.8 kg Ca, and 9.9 kg Ca ha?1 per season, respectively. The trees sprayed with water were treated as the control. The results showed that Ca sprays caused no leaf and fruit injury. Calcium spray measures did not affect yield, mean fruit weight, and soluble solids concentration (SSC), titratable acidity and starch index of fruit at harvest. However, at harvest apples sprayed with Ca contained more this nutrient and were firmer than those of the control plots. After storage apples sprayed with Ca had more acids, and were firmer and less liable to bitter pit than the control fruit. Calcium sprays did not affect SSC of fruit after storage but reduced postharvest decay of fruit caused by Peziculla spp. and Penicillium expansum fungi. Apples sprayed with Insol Wap material were the least affected by the above pathogens. It is concluded that in apple orchards preharvest sprays of a mixture of Ca-formate, Ca-acetate, CaCl2 and Ca(NO3)2, containing 10% Ca (w/w) with ca. 50% in an organic form, can be the alternative to sprays of CaCl2 or Ca(NO3)2. 相似文献