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On the Performances of Classical VAR and Sims-Zha Bayesian VAR models in the Presence of Collinearity and Autocorrelated Error Terms

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Open Journal of Statistics 2016年第1期6卷 96-132页

作者： m. O. Adenomon V. A. michael O. P. evans Department of mathematics & Statistics The Federal Polytechnic Bida Nigeria

In time series literature, many authors have found out that multicollinearity and autocorrelation usually afflict time series data. In this paper, we compare the performances of classical VAR and Sims-Zha Bayesian VAR models with quadratic decay on bivariate time series data jointly influenced by collinearity and autocorrelation. We simulate bivariate time series data for different collinearity levels (﹣0.99, ﹣0.95, ﹣0.9, ﹣0.85, ﹣0.8, 0.8, 0.85, 0.9, 0.95, 0.99) and autocorrelation levels (﹣0.99, ﹣0.95, ﹣0.9, ﹣0.85, ﹣0.8, 0.8, 0.85, 0.9, 0.95, 0.99) for time series length of 8, 16, 32, 64, 128, 256 respectively. The results from 10,000 simulations reveal that the models performance varies with the collinearity and autocorrelation levels, and with the time series lengths. In addition, the results reveal that the BVAR4 model is a viable model for forecasting. Therefore, we recommend that the levels of collinearity and autocorrelation, and the time series length should be considered in using an appropriate model for forecasting.

关键词： Vector Autoregression (VAR) Classical VAR Bayesian VAR (BVAR) Sims-Zha Prior Collinearity Autocorrelation

A comparison of the nutritive value of perennial ryegrass,perennial ryegrass and white clover and multispecies-based farmlet systems

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Grassland Research 2023年第2期2卷 129-139页

作者： Shona Baker mary B.Lynch Fionnuala Godwin Tommy m.Boland Alexander C.O.evans Paul N.C.murphy Alan K.Kelly Helen Sheridan11 UCD School of Agriculture and Food Science University College DublinBelfieldIreland Teagasc Environmental Research Centre Johnstown Castle Co.WexfordIreland UCD Earth Institute University College DublinBelfieldIreland

Background:Limited information is available regarding the nutritive value and structural characteristics of multispecies swards when rotationally ***:Three farmlet types were investigated in terms of their nutritive value:Lolium perenne(LP);***+Trifolium repens(LP+TR);and a multispecies sward containing grasses,legumes and herbs(mSS).Farmlets were stocked with beef steers(2.5 livestock units ha−1),grazed on a 1 ha scale to 6 cm(mSS)and 4 cm(LP and LP+TR)***:A greater ash concentration was found in mSS than LP(84 vs.75 g kg−1 Dm).Both LP+TR and mSS had higher crude protein and lower neutral detergent fibre concentrations than *** relative ranking of water soluble carbohydrate and dry matter(Dm)concentration was LP>LP+TR>*** the leaf component of the LP farmlet contributing more to herbage Dm,the organic matter digestibilities of the swards were ***:The mSS and LP+TR farmlets achieved similar forage quality under intensive grazing to ***,it is worth noting that mSS had a higher concentration of acid detergent lignin,which can negatively impact *** investigation is needed to determine optimal grazing management practices that can minimise the effects of higher lignin concentration on digestibility in multispecies swards.

关键词： forage herbs forage quality grazing cattle legumes multispecies swards nitrogen sustainability

Three co-located resistance genes confer resistance to leaf rust and stripe rust in wheat variety Borlaug 100

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The Crop Journal 2022年第2期10卷 490-497页

作者： Bowei Ye Ravi P.Singh Chan Yuan Demei Liu mandeep S.Randhawa Julio Huerta-Espino Sridhar Bhavani evans Lagudah Caixia Lan College of Plant Science&Technology Huazhong Agricultural UniversityWuhan 430070HubeiChina International maize and Wheat Improvement Center(CImmYT) Apdo.Postal 6-64106600 Mexico D.F.Mexico Qinghai Provincial Key Laboratory of Crop molecular Breeding Northwest Institute of Plateau BiologyChinese Academy of ScienceXining 810008QinghaiChina Campo Experimental Valle de méxico INIFAP Apdo.Postal 1056230ChapingoEdo.de MexicoMexico CSIRO Agriculture&Food GPO Box 1600CanberraACT 2601Australia

Leaf rust(LR) and stripe rust(YR) are important diseases in wheat producing areas worldwide and cause severe yield losses under favorable environmental conditions when susceptible varieties are grown. We determined the genetic basis of resistance to LR and YR in variety Borlaug 100 by developing and phenotyping a population of 198 F6 recombinant inbred lines derived from a cross with the susceptible parent Apav#1. LR and YR phenotyping were conducted for 4 and 3 seasons, respectively, at CImmYT research stations in mexico under artificial epidemics. mendelian segregation analyses indicated that 3–5 LR and 2 YR genes conferred resistance in Borlaug 100. Lr46/Yr29(1 BL), Yr17(2 AS) and Yr30(3 BS) were present in the resistant parent and segregated in the RIL population based on characterization by molecular markers linked to these genes. When present alone, Lr46/Yr29 caused average 13% and 16% reductions in LR and YR severities, respectively, in RILs. Similarly, Yr17 and Yr30 reduced YR severities by 57% and 11%, respectively. The Yr30 and the Yr17 translocation were also associated with 27% and 14% reductions, respectively, in LR severity, indicating that the 3 BS and 2 AS chromosomal regions likely carry new slow rusting LR resistance genes, temporarily designated as Lr B1 and Lr B2, respectively. Additive effects of Yr30*Yr17, Yr29*Yr17 and Yr29*Yr30 on YR and LR were significant and reduced YR severities by 56%,55%, and 45%, respectively, and LR severities by 34%, 40%, and 45%, respectively. Furthermore, interaction between the three genes was also significant, with mean reductions of 70% for YR and 54% for LR severities. Borlaug 100, or any one of the 21 lines with variable agronomic traits but carrying all three colocated resistance loci, can be used as resistance sources in wheat breeding programs.

关键词： Co-located resistance loci Common wheat Gene interaction Puccinia triticina Puccinia striiformis Triticum aestivum

mgO/γ-Al_2O_3烷氧基化催化剂制备及结构与性能研究

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精细化工 2003年第2期20卷 74-77页

作者：张蕊李殿卿张法智 D.G.evans 段雪北京化工大学可控化学反应科学与技术基础教育部重点实验室北京100029

在γ Al2 O3 载体上浸渍mg (NO3 ) 2 ·6H2 O ,然后分别经 40 0、45 0和 5 0 0℃焙烧制成mgO/γ Al2 O3 固体碱催化剂。结果表明 ,mgO在γ Al2 O3 载体表面具有单层分散性质 ,当mgO的负载量低于某一数值 (阈值 )时 ,从样品的X光粉末衍... 详细信息

在γ Al2 O3 载体上浸渍mg (NO3 ) 2 ·6H2 O ,然后分别经 40 0、45 0和 5 0 0℃焙烧制成mgO/γ Al2 O3 固体碱催化剂。结果表明 ,mgO在γ Al2 O3 载体表面具有单层分散性质 ,当mgO的负载量低于某一数值 (阈值 )时 ,从样品的X光粉末衍射谱图上观察不到mgO的特征衍射峰 ,负载量超过阈值时开始出现mgO的晶相 ,且mgO的XRD衍射峰强度随mgO的负载量的增加而增加 ,其单分散阈值为 0 0 80 gmgO/ 10 0m2 γ Al2 O3 。应用CO2 TPD技术测定了样品的碱性 ,结果表明 ,样品在接近阈值时其碱量大幅度增加 ,碱强度提高。样品的比表面最初随着mgO负载量的增加而下降 ,但达阈值后基本保持不变。

关键词：制备结构性能研究 mgO/γ-Al2O3 烷氧基化催化剂单层分散阈值

A Simulation Study on the Performances of Classical Var and Sims-Zha Bayesian Var models in the Presence of Autocorrelated Errors

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Open Journal of modelling and Simulation 2015年第4期3卷 146-158页

作者： m. O. Adenomon V. A. michael O. P. evans Department of mathematics & Statistics The Federal Polytechnic Bida Nigeria

It is well known that a high degree of positive dependency among the errors generally leads to 1) serious underestimation of standard errors for regression coefficients;2) prediction intervals that are excessively wide. This paper set out to study the performances of classical VAR and Sims-Zha Bayesian VAR models in the presence of autocorrelated errors. Autocorrelation levels of (-0.99, -0.95, -0.9, -0.85, -0.8, 0.8, 0.85, 0.9, 0.95, 0.99) were considered for short term (T = 8, 16);medium term (T = 32, 64) and long term (T = 128, 256). The results from 10,000 simulation revealed that BVAR model with loose prior is suitable for negative autocorrelations and BVAR model with tight prior is suitable for positive autocorrelations in the short term. While for medium term, the BVAR model with loose prior is suitable for the autocorrelation levels considered except in few cases. Lastly, for long term, the classical VAR is suitable for all the autocorrelation levels considered except in some cases where the BVAR models are preferred. This work therefore concludes that the performance of the classical VAR and Sims-Zha Bayesian VAR varies in terms of the autocorrelation levels and the time series lengths.

关键词： Simulation Performances Vector Autoregression (VAR) Classical VAR Sims-Zha Prior Bayesian VAR (BVAR) Autocorrelated Errors

Short Term Forecasting Performances of Classical VAR and Sims-Zha Bayesian VAR models for Time Series with Collinear Variables and Correlated Error Terms

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Open Journal of Statistics 2015年第7期5卷 742-753页

作者： m. O. Adenomon V. A. michael O. P. evans Department of mathematics & Statistics The Federal Polytechnic Bida Nigeria

Forecasts can either be short term, medium term or long term. In this work we considered short term forecast because of the problem of limited data or time series data that is often encounter in time series analysis. This simulation study considered the performances of the classical VAR and Sims-Zha Bayesian VAR for short term series at different levels of collinearity and correlated error terms. The results from 10,000 iteration revealed that the BVAR models are excellent for time series length of T=8 for all levels of collinearity while the classical VAR is effective for time series length of T=16 for all collinearity levels except when ρ = -0.9 and ρ = -0.95. We therefore recommended that for effective short term forecasting, the time series length, forecasting horizon and the collinearity level should be considered.

关键词： Short term Forecasting Vector Autoregressive (VAR) Bayesian VAR (BVAR) Sims-Zha Prior Collinearity Error Terms

Intestinal Staple Line Reinforcement Using matriStem

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Surgical Science 2015年第2期6卷 65-70页

作者： Kent C. Sasse David Warner Sean m. Ward Walter mandeville Rebecca evans Department of Physiology & Cell Biology University of Nevada School of Medicine Reno USA

Background: Staple line reinforcement material has been demonstrated to raise the burst pressure threshold after linear intestinal stapling. Numerous bioprosthetic materials have been utilized in surgical practice. Porcine urinary bladder matrix (ACell, Inc.) is an extracellular matrix material derived from porcine bladder used to reinforce surgically repaired soft tissue, and facilitate the body’s regenerative capacity. Objective: This study represents the first evaluation of urinary bladder matrix in gastrointestinal staple line reinforcement. methods: Pathogen-free pigs underwent midline laparotomy under general anesthesia. Small intestinal division was performed with an endoscopic linear stapler. Nineteen intestinal divisions were performed with urinary bladder matrix staple line reinforcement, and twenty divisions were unreinforced. Staple lines were then subjected to burst pressure analysis by intraluminal infusion of dyed Krebs solution at an infusion rate of 20 ml·min-1 under manometric monitoring. Upon visible staple line extravasation, intraluminal pressure was recorded. Results: Intestinal staple lines reinforced with urinary bladder matrix exhibited significantly higher burst pressure threshold (p mmHg, compared to 61 ± 37 mmHg for unreinforced staple lines. Conclusion: Staple line reinforcement using urinary bladder matrix acutely improves burst pressures of intestinal staple lines when compared with unreinforced staple lines. Its regenerative properties may confer a long-term advantage to staple line reinforcement. These findings, along with previous findings of constructive remodeling in the presence of urinary bladder matrix in treatment of the gastrointestinal system, suggest that UBm may serve a role in gastrointestinal staple line reinforcement.

关键词： Surgical Staples Extracellular matrix Porcine Urinary Bladder matrix Surgical Anastomosis Small Intestine

Comparative Bioremediation of Petroleum Hydrocarbon-Contaminated Soil by Biostimulation, Bioaugmentation and Surfactant Addition

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Journal of Environmental Science and Engineering(A) 2012年第5期1卷 637-650页

作者： Elise A. Asquith Phillip m. Geary Annette L. Nolan Craig A. evans School of Environmental and Life Sciences The University of Newcastle NSW 2308 Australia Enviropacific Services PrY Ltd. NSW 2297 Australia

A bench-scale biopiling experiment was conducted to hydrocarbon bioremediation in a chronically contaminated soil compare the ability of different techniques to enhance petroleum After 195 days, 10%-32% removal of TPHs （total petroleum hydrocarbons） occurred in unamended soil （control）. Biostimulation by inorganic nutrient addition enhanced TPH removal （49%） confirming that bioremediation was nutrient limited and the soil contained a well-adapted hydrocarbonoclastic microbial community. The addition of organic amendments including green waste at 25% and 50% （w/w） and a commercial product called DaramendTm had a further biostimulatory effect （50%-66%, 34%-59% and 69%-80% TPH removal respectively）. Bioaugmentation using two commercially available petroleum hydrocarbon degrading microbial cultures with nutrients enhanced TPH removal in the case of RemActivTm （60%-69%）, but had a marginal effect using Recycler 102 （49%-55%）. The effect of a non-ionic surfactant in green waste amended soil was variable （52%-72% TPH reduction）, but its potential to enhance biodegradation presumably by promoting contaminant bioavailability was demonstrated. High degradation of artificially added polycyclic aromatic hydrocarbons （PAHs） occurred after 106 days （75%-84%）, but significant differences between the control and treatments were unapparent, suggesting that spiked soils do not reflect the behavior of contaminants in genuinely polluted and weathered soil.

关键词： Bioremediation petroleum hydrocarbons bioaugmentation biostimulation surfactant.

Elucidating regulatory processes of intense physical activity by multi-omics analysis

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military medical Research 2024年第4期11卷 479-499页

作者： Ernesto S.Nakayasu marina A.Gritsenko Young-mo Kim Jennifer E.Kyle Kelly G.Stratton Carrie D.Nicora Nathalie munoz Kathleen m.Navarro Daniel Claborne Yuqian Gao Karl K.Weitz Vanessa L.Paurus Kent J.Bloodsworth kelsey A.Allen Lisa m.Bramer Fernando montes Kathleen A.Clark Grant Tietje Justin Teeguarden Kristin E.Burnum-Johnson Biological Sciences Division Pacific Northwest National LaboratoryRichlandWA 99352USA Environmental and molecular Sciences Division Pacific Northwest National LaboratoryRichlandWA 99352USA Centers for Disease Control and Prevention National Institute for Occupational Safety and HealthWestern States DivisionDenverCO 80204USA Computational Analytics Division Pacific Northwest National LaboratoryRichlandWA 99352USA National Security Directorate Pacific Northwest National LaboratoryRichlandWA 99352USA Los Angeles County Fire Department Los AngelesCA 90063USA Centers for Disease Control and Prevention National Institute for Occupational Safety and HealthRespiratory Health DivisionMorgantownWV 26505USA Environmental and molecular Toxicology Oregon State UniversityCorvallisOR 97331USA

Background:Physiological and biochemical processes across tissues of the body are regulated in response to the high demands of intense physical activity in several occupations,such as firefighting,law enforcement,military,and sports.A better understanding of such processes can ultimately help improve human performance and prevent illnesses in the work ***:To study regulatory processes in intense physical activity simulating real-life conditions,we performed a multi-omics analysis of 3 biofluids(blood plasma,urine,and saliva)collected from 11 wildland firefighters before and after a 45 min,intense exercise *** profiles ***-exercise were compared by Student’s t-test followed by pathway analysis and comparison between the different omics ***:Our multi-omics analysis identified and quantified 3835 proteins,730 lipids and 182 metabolites combining the 3 different types of *** blood plasma analysis revealed signatures of tissue damage and acute repair response accompanied by enhanced carbon metabolism to meet energy *** urine analysis showed a strong,concomitant regulation of 6 out of 8 identified proteins from the renin-angiotensin system supporting increased excretion of catabolites,reabsorption of nutrients and maintenance of fluid *** saliva,we observed a decrease in 3 pro-inflammatory cytokines and an increase in 8 antimicrobial peptides.A systematic literature review identified 6 papers that support an altered susceptibility to respiratory ***:This study shows simultaneous regulatory signatures in biofluids indicative of homeostatic maintenance during intense physical activity with possible effects on increased infection susceptibility,suggesting that caution against respiratory diseases could benefit workers on highly physical demanding jobs.

关键词： multi-omics analysis Intense exercise Human performance Biofluids metabolism Immunity