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Why ecosystem characteristics predicted from remotely sensed data are unbiased and biased at the same time-and how this affects applications

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Forest Ecosystems 2024年第1期11卷 24-31页

作者： Goran Ståhl Terje Gobakken Svetlana Saarela Henrik J.Persson Magnus ekstrom Sean P.Healey Zhiqiang Yang Johan Holmgren Eva Lindberg Kenneth Nystrom Emanuele Papucci Patrik Ulvdal Hans OleØrka erik Næsset Zhengyang Hou Håkan Olsson Ronald E.McRoberts Department of Forest Resource Management Swedish University of Agricultural Sciences90183UmeåSweden Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life SciencesÅsNorway USDA Forest Service Rocky Mountain Research StationOgdenUTUSA The Key Laboratory for Silviculture and Conservation of Ministry of Education Beijing Forestry UniversityBeijing100083China Department of Forest Resources University of MinnesotaSt.PaulMNUSA

Remotely sensed data are frequently used for predicting and mapping ecosystem characteristics,and spatially explicit wall-to-wall information is sometimes proposed as the best possible source of information for ***,wall-to-wall information typically relies on model-based prediction,and several features of model-based prediction should be understood before extensively relying on this type of *** such feature is that model-based predictors can be considered both unbiased and biased at the same time,which has important implications in several areas of *** this discussion paper,we first describe the conventional model-unbiasedness paradigm that underpins most prediction techniques using remotely sensed(or other)auxiliary *** this point of view,model-based predictors are typically ***,we show that for specific domains,identified based on their true values,the same model-based predictors can be considered biased,and sometimes severely *** suggest distinguishing between conventional model-bias,defined in the statistical literature as the difference between the expected value of a predictor and the expected value of the quantity being predicted,and design-bias of model-based estimators,defined as the difference between the expected value of a model-based estimator and the true value of the quantity being *** show that model-based estimators(or predictors)are typically design-biased,and that there is a trend in the design-bias from overestimating small true values to underestimating large true ***,we give examples of applications where this is important to acknowledge and to potentially make adjustments to correct for the design-bias *** argue that relying entirely on conventional model-unbiasedness may lead to mistakes in several areas of application that use predictions from remotely sensed data.

关键词： Bias Model-based inference Design-based inference

Metabolomic, Transcriptional, Hormonal, and Signaling Cross-Talk in Superroot2

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Molecular Plant 2010年第1期3卷 192-211页

作者： Marc Morant Claus ekstrom Peter Ulvskov Charlotte Kristensen Mats Rudemo Carl erik Olsen Jorgen Hansen Kirsten Jorgensena Bodil Jorgensen Birger Lindberg Moilera Soren Bak Plant Biochemistry Laboratory Department of Plant Biology and Biotechnology University of Copenhagen 40 Thorvaldsensvej DK-1871 FrederiksbergC Copenhagen Denmark Center for Molecular Plant Physiology University of Copenhagen. DK-1871 Frederiksberg C Copenhagen Denmark Department of Natural Sciences University of Copenhagen DK-1871 Frederiksberg C Copenhagen Denmark VKR research centre 'Pro-Active Plants' Plant Biochemistry Laboratory Department of Plant Biology and Biotechnology University of Copenhagen DK-1871 Frederiksberg C Copenhagen Denmark Evolva A/S Bulowsvej 25 DK-1870 Frederiksberg C Copenhagen Denmark Center for Applied Bioinformatics at LIFE University of Copenhagen 40 Thorvaldsensvej DK-1871 Frederiksberg C Copenhagen Denmark

Auxin homeostasis is pivotal for normal plant growth and development. The superroot2 （sur2） mutant was initially isolated in a forward genetic screen for auxin overproducers, and SUR2 was suggested to control auxin conju- gation and thereby regulate auxin homeostasis. However, the phenotype was not uniform and could not be described as a pure high auxin phenotype, indicating that knockout of CYP83B1 has multiple effects. Subsequently, SUR2 was identified as CYP83B1, a cytochrome P450 positioned at the metabolic branch point between auxin and indole glucosinolate metabolism. To investigate concomitant global alterations triggered by knockout of CYP83B1 and the countermeasures chosen by the mutant to cope with hormonal and metabolic imbalances, 10-day-old mutant seedlings were characterized with respect to their transcriptome and metabolome profiles. Here, we report a global analysis of the sur2 mutant by the use of a combined transcriptomic and metabolomic approach revealing pronounced effects on several metabolic grids including the intersection between secondary metabolism, cell wall turnover, hormone metabolism, and stress responses. Metabolic and transcriptional cross-talks in sur2 were found to be regulated by complex interactions between both positively and negatively acting transcription factors. The complex phenotype of sur2 may thus not only be assigned to elevated levels of auxin, but also to ethylene and abscisic acid responses as well as drought responses in the absence of a water deficiency. The delicate balance between these signals explains why minute changes in growth conditions may result in the non-uniform phenotype. The large phenotypic variation observed between and within the different surveys may be reconciled by the complex and intricate hormonal balances in sur2 seedlings decoded in this study.

关键词： Abiotic/environmental stress hormonal regulation metabolomics secondary metabolism/natural products transcriptome analysis development.

Low serum albumin predicts early mortality in patients with severe hypoxic hepatitis

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World Journal of Hepatology 2017年第22期9卷 959-966页

作者： Pik-Eu Chang Boon-Bee George Goh Victoria ekstrom Ming-Liang Ong Chee-Kiat Tan Department of Gastro enterology and Hepatology Singapore General Hospital Duke-NUS Medical School

To evaluate the incidence, etiology, and predictors of mortality of severe hypoxic hepatitis. METHODSWe used computerized patient records to identify consecutive cases of severe hypoxic hepatitis admitted to a tertiary hospital in Singapore over a one-year period. We defined severe hypoxic hepatitis as elevation of serum transaminases more than 100 times upper limit of normal in the clinical setting of cardiac, circulatory or respiratory failure after exclusion of other causes of hepatitis. We used multivariable regression analysis to determine predictors for mortality. RESULTSWe identified 75 cases of severe hypoxic hepatitis out of 71380 hospital admissions over one year, providing an incidence of 1.05 cases per 1000 admissions. Median age was 65 years (range 19-88); 57.3% males. The most common etiologies of severe hypoxic hepatitis were acute myocardial infarction and sepsis. Fifty-three patients (71%) died during the hospitalization. The sole independent predictive factor for mortality was serum albumin measured at the onset of severe hypoxic hepatitis. Patients with low serum albumin of less than 28 g/L have more than five-fold increase risk of death (OR = 5.39, 95%CI: 1.85-15.71). CONCLUSIONSevere hypoxic hepatitis is uncommon but has a high mortality rate. Patients with low serum albumin are at highest risk of death.

关键词： Severe Mortality Albumin Incidence Hypoxic hepatitis Predictors Etiology Prognosis

Real world experience with Pegylated Interferon and ribavirin in Hepatitis C Genotype 1 population with favourable IL28B polymorphism

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Gastroenterology Report 2017年第3期5卷 208-212,I0002页

作者： Victoria ekstrom Rajneesh Kumar Yi Zhao Mei Ling Yee Cynthia Sung Dorothy Toh Poh Yen Loh Jessica Tan Eng Kiong Teo Wan Cheng Chow Department of Gastroenterology and Hepatology Singapore General HospitalSingapore Department of Clinical Translational Research Singapore General HospitalSingapore Department of Pharmacy Singapore General HospitalSingapore Health Products Regulation Group Health Sciences AuthoritySingapore Emerging Infectious Disease Programme Duke-NUS Medical SchoolSingapore Department of Gastroenterology and Hepatology Changi General HospitalSingapore

Background and aim:Conventional hepatitis C treatment using pegylated interferon(PEG-IFN)and ribavirin is associated with significant side ***28B polymorphism can predict response to treatment,with CC genotype having a better *** gene deficiency protects against clinically significant anaemia induced by *** purpose of this study was to determine IL28B polymorphismand ITPA variation among hepatitis C genotype 1 patients who have undergone therapy with PEG-IFN and ribavirin and their association with sustained viral response(SVR).Methods:All hepatitis C genotype 1 patients who had been treated with PEG-IFN and ribavirin over the past 10 years were identified by available medical records and were contacted by letter of invitation to participate in the *** samples for IL28B and ITPA genotyping were *** records were reviewed for verification of treatment response,development of anaemia and if treatment reduction was required during the ***:A total of 61 patients with hepatitis C genotype 1 were treated with PEG-IFN and ribavirin,of whom 42 agreed to participate in the *** age was 45.6±12.9 years at time of treatment,and 83.3%of patients ***-three(78.6%)had IL28B CC genotype,of whom 25(75.8%)obtained SVR compared with only 3 of 9(33.3%)non C/C genotype patients who achieved SVR(P=0.041).Eleven(26.1%)patients had ITPA AC genotype,and 30(71.4%)had CC *** was no statistically significant difference between ITPA AC and CC genotypes in predicting clinically significant anaemia(45.5%vs 63.3%,P=0.302).Even among patients who developed anaemia,70.8%stillmanaged to achieve *** reduction also had no impact on ***:Hepatitis C genotype 1 patients should be informed of the response rate for treatment with PEG-IFN and ribavirin in a population with favourable IL28B genotype before consideration of newer therapeutic options.

关键词： hepatitis C pegylated interferon IL28B polymorphism sustained viral response

A Study into Digital Dermatitis Transmission and Bacterial Associated Pathological Changes Involved in the Disease

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Open Journal of Veterinary Medicine 2013年第2期3卷 192-198页

作者： N.Capion M.Boye C.ekstrom K.Dupont T.K.Jensen Department of Large Animal Sciences Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark National Veterinary Institute Technical University of DenmarkCopenhagenDenmark Department of Biostatistics University of Southern DenmarkOdenseDenmark

Digital dermatitis is a highly prevalent painful lesion affecting the feet in dairy cattle. Even though the pathogenesis has been subject of investigation since 1974, there is still a lack of knowledge about the spread of the disease among cows within a herd as well as between herds. The purpose of this study was to monitor transmission of digital dermatitis under experimental conditions between naive heifers and affected animals, to monitor the changes in clinical appearance, microbial colonisation of the skin as lesions progressed and to apply a q-PCR for the detection of Treponema spp. in faecal samples. Eight heifers with clinical normal digital skin were housed with 5 heifers with severe digital dermatitis lesion for 8 weeks on a solid concrete floor with an accumulating layer of slurry. Digital skin was examined daily and lesions were clinically scored. Skin biopsies were taken from the healthy heifers at introduction and weekly from all lesions for histopathological evaluation and fluorescence in situ hybridization. None of the healthy heifers developed digital dermatitis and in 4 out of 5 infected heifers the lesions healed during the study. All samples from healthy skin were negative for Treponema spp. and one sample were positive for Dichelobacter nodosus. Colonization of healthy skin could not be identified in this study. There was no significant relation between clinical scoring of the lesions and histopathological score and the presence of Treponema spp. There were however a significant relation between the prevalence of Treponema spp. in the skin and severity of changes in epidermis and dermis. By qPCR all the healthy heifers were found to excrete Treponema spp. in their faeces.

关键词： Digital Dermatitis Treponema spp. Histopathology Infection Dynamics

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地震学和IRIS

世界地震译丛 1997年第5期28卷 3-5页

作者： G.ekstrom 刘希玲国家地震局地球物理研究所

地震学的一个最重要的特征是,我们所研究的对象——地震——看起来是不可预测的和特殊的。我们还远未达到从基本定律出发的、对地震的全面了解,而且很少有机会能进行可控实验,来分离出控制地震发生的特殊的物理条件。然而,根据地震观测... 详细信息

地震学的一个最重要的特征是,我们所研究的对象——地震——看起来是不可预测的和特殊的。我们还远未达到从基本定律出发的、对地震的全面了解,而且很少有机会能进行可控实验,来分离出控制地震发生的特殊的物理条件。然而,根据地震观测结果的长期积累,导致地震活动的构造过程的描述以及震源的运动学和动力学模型已得到很大的发展。对于对导致地震孕育的地质条件和地质过程感兴趣的地震学家来说,要在地质构造的存在或范围上或者一个区域变形模式方面得出结论,一次地震的发生,记录和分析能提供足够的信息。地震学家研究地震断裂机制时,一个地震的高质量的记录可以为假设的震源模式提供一个新的约束。较好的地震资料有时有助于证明或证伪称有争议的假说,但更经常地是导致物理模型和概念的渐近式的进化。地震的复杂性和多变性使高质量的观测资料的汇集成为我们这门科学研究的中心内容。在与地震震源相关的广泛的科学问题中,IRIS设备已经取得了可能的成就。除了由于由IRIS仪器收集的地震数据数量和质量的提高带来的优势外,还在IRIS设备的协助下,在地震数据如何分享、管理和分配方面产生了深刻的变化。这篇短文的目的在于以下三个方面:首先,强调IRIS在技术和组织方面的成就,这些成就导致了1994年两次千载难逢的深震的观测。第二,讨论IRIS设备如何才能够有助于解决目前震源理论方面的一些争论。最后,描述怎样用新方法将这些日益增加的高质量的地震数据用于监控全球地震和应力释放,以及这些数据的迅速传播和分析怎样产生社会效益。

关键词：地震学 IRIS 震源模型地震活动

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混合动力汽车零排放的研究

汽车与新动力 2020年第5期3卷 45-53页

作者： [瑞典]M.LAURELL [瑞典]L.PACE [瑞典]F.ekstrom [瑞典]K.KONIECZNY 武涛(译) 不详

目前,装配点燃式发动机的乘用车和轻型货车在热机状态下已经实现了对排气污染物的完全转化,但减少排放的目标仍面临挑战。这主要受到冷起动和暖机策略的影响。对排气后处理系统技术研究的重点是热管理,并希望发动机尽快达到热机状态。目... 详细信息

目前,装配点燃式发动机的乘用车和轻型货车在热机状态下已经实现了对排气污染物的完全转化,但减少排放的目标仍面临挑战。这主要受到冷起动和暖机策略的影响。对排气后处理系统技术研究的重点是热管理,并希望发动机尽快达到热机状态。目前,新的挑战是实际驾驶工况排放(RDE)法规,因为RDE法规包含更频繁的不同冷起动工况,这与以前法规要求的测试循环迥然不同。另一方面,如果排气能实现完全转化,对于许多排气后处理系统(EATS)部件来说是有益的。例如,如果可以降低排气温度,则有利于排气系统的耐久性。为了进一步大幅度降低排放,实现零排放概念,研究了电加热催化器(EHC)技术,同时也包括预热策略。排气后处理明确的目标是在合适的时间、位置获得合适的温度。对排气后处理系统结构、EHC加热策略等多种方案进行了研究,以实现显著的冷起动减排。混合动力电动汽车(HEV)的应用正快速地增长,这为支持新的减排策略提供了更多的可能性。该方案不仅能借助额外的电力驱动,还包括由电能支持的排气后处理系统设计。沃尔沃汽车和大陆Emitec公司已经对嵌入EHC型的排气后处理系统进行了设计和研究。当然,平衡排放与车辆的其他特性(如燃油耗)也很重要。

关键词：电加热催化器零排放排气后处理系统混合动力冷起动

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夏日俪影

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采用有机朗肯循环废热回收的轻度混合动力火花点火涡轮增压轿车柴油机

作者： P.O.·艾克斯特隆姆(P.O. ekstrom)

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汽车与新动力 2020年第6期3卷 41-47页

作者： [瑞典]F.B.ekstrom [瑞典]O.ROLANDSON [瑞典]S.erikSSON [瑞典]C.ODENMARCK [瑞典]M.svenSSON [瑞典]A.erikSSON [瑞典]H.OLSEN 闫红梅(译) 不详

汽车制造商在努力制造更节油的车辆时,会考虑采取一切可能的措施来提高内燃机动力系统的效率。其中,48V轻度混合动力技术即是节油措施之一。采用米勒技术的火花点火直喷发动机和从发动机废热中回收能量也是节油措施的一种。研究沃尔沃... 详细信息

汽车制造商在努力制造更节油的车辆时,会考虑采取一切可能的措施来提高内燃机动力系统的效率。其中,48V轻度混合动力技术即是节油措施之一。采用米勒技术的火花点火直喷发动机和从发动机废热中回收能量也是节油措施的一种。研究沃尔沃轿车基于乙醇的有机朗肯循环废热回收系统,围绕4缸2.0L的火花点燃发动机成功构建,运用48V轻度混合动力技术的同时考虑了车辆的安装需求。本研究还为有机朗肯循环系统开发了专用的控制系统,包括其与发动机之间的通信。有机朗肯循环系统使用发动机废气作为热源,为此设计制造专用的蒸发器以适合车辆的腔道。乙醇蒸气的膨胀发生在轴向活塞式膨胀机中,该轴向活塞式膨胀机通过皮带传动,既与混合动力系统电气耦合,又与发动机曲轴机械耦合。研究发现,该膨胀机的这种双重动力输出对于具有瞬态驾驶的乘用车尤为重要,可以通过电动混合系统的快速响应来克服蒸气系统的缓慢响应,从而提供了更多废热能回收的机会。发动机测试台架试验的结果表明,在发动机高负荷下,采用化学计量比运行时,制动比油耗降低了5%~7%,与模拟结果一致。这表明组合动力总成系统在城市、城郊和高速工况方面均具有优势。

关键词：有机朗肯循环废热回收轻度混合动力能量转换涡轮增压轿车柴油机